Only app administrators could create new Wallit walls, and users had to be in relative proximity to a place to properly use the app.

Wallit has now torn down those walls to the app. Starting today, users can create a virtual wall anywhere, from their office to their living room to a party at a friend’s place.

Since the whole idea of writing on virtual walls could be a bit confusing to those who haven’t seen the app, there’s a video below to help show how it works.

Basically, Wallit app users have the option to leave a note on a virtual wall that’s superimposed over a real location. Depending on whether the wall is private or not, users within Wallit’s social network can use their phone’s camera to capture an image of that building or structure — such as the Golden Gate Bridge, for example — and see what people have written around it, as well as other data that might be available.

Augmented reality apps that show contextual info based on your location are hardly new, though Wallit does add an interesting social twist to AR. Mobile apps like Wikitude and Google Goggles display info about your surroundings on a smartphone screen and, of course, Google’s Project X glasses aim to remove the smartphone from the whole equation, and instead show relevant local information through a wearable device.

The Wallit app is free, and right now the 700 existing walls don’t show any ads. However, Wallit creator Veysel Berk says that “value walls” may be a part of the app in the future, where brands will customize certain walls. Whether that means ads will appear on already existing virtual walls, or whether the ad walls will be completely separate, is still unclear.

The app can be found here in the iTunes store. It’s currently only available for iOS devices, though Berk says an Android version is in the works.

Apple claims Macs to be more secure than Windows PCs. In the light of recent malware attacks on the Mac platform, there are several articles on the Web questioning this claim. What is your take on this matter?

A:

Macs aren’t invulnerable to malicious software. No computer is. But the people who produce viruses and spyware have traditionally focused on Windows—and still do, primarily. There have indeed been a couple of recent instances of malware that spread among some Macs in the real world. But bear in mind that, despite the steady growth in Mac sales, Windows still powers the vast majority of the world’s PCs, and, because of that, there are hundreds of thousands of malicious programs targeting it, versus just a handful of known ones for the Mac.

So, my take on this is that while Mac users must be careful where they surf, and Apple will have to step up its game against these attacks, an unprotected Macintosh is still, in daily use, far less likely to become infected than an unprotected Windows PC. How users handle this depends on their habits and their tolerance, both for risk, and for the downsides of constantly running security software, which can sap resources and be annoying. I advise all Windows users to run such software. But I see it as optional for Mac users, at least today. Time will tell if that changes.

Q:

Do you know of any apps that work well with dictation on older iPhones?

A:

One that I have used successfully is Dragon Dictation from Nuance. The same company makes an Android app called FlexT9, which I haven’t tested, that includes dictation, among other features. Both apps work on a wide variety of models.

Q:

I love my BlackBerry for the ease of emailing and maintaining my schedule but not for accessing the Internet. I am a T-Mobile customer. Is there any device that has the good features of the BlackBerry and also easily and comprehensively accesses the Internet?

A:

T-Mobile offers a wide range of Android phones that include very good Web browsers and typically have two email apps: one for Gmail and one for all your other email accounts. They also have calendar apps.

Overall, I prefer these smartphones to current BlackBerrys and find the email experience fine. But people who are used to the BlackBerry for email—especially corporate email—sometimes complain that email on other devices isn’t as fast. This is partly because BlackBerry email is routed through a proprietary system. I’d advise asking friends or colleagues with newer T-Mobile Android phones about their email experience.

Write to Walt at mossberg.@wsj.com.

I tested an idea that aims to change that practice: Appy Couple. It functions as a couple’s official wedding app and guides guests through a wedding. They can use it to track information about the bachelorette party or other pre-wedding events, and on the wedding day to find their way to the venue and post photos that they take. While many existing wedding apps help brides and grooms plan things like seating arrangements, dress selections and registry creation, this app is a mobile aid for guests.

Appy Couple comes from a New York City-based start-up called AppeProPo Inc., and it has a couple of rough edges. For example, users can’t crop uploaded images and it is difficult to navigate the section where virtual Champagne toasts can be posted. The company plans to fix these issues soon.

Appy Couple has features tailored for guests, who can upload photos, get travel and weather information and vote in polls.

Last year, I spent weeks making my own wedding website, and very few of my tech-savvy guests used it or visited it more than once—if at all. I only wish Appy Couple had been available for my wedding, where most guests carried iPhones or Android phones.

This app-creating website is currently free to use, and it will always be free for guests to download; they follow an email link or use a provided code to access their couple’s wedding app. Readers of this column can create their own wedding apps on AppyCouple.com using their email addresses and “AppyPreview” as a code, since it is currently usable by invitation-only. In the fall, AppeProPo will start charging couples to make apps: Some designs will cost $49, while limited-edition and designer-series app templates will cost $99 to $200 each. One hundred designs are available now, and 50 more are coming by fall.

Appy Couple works on iPhones, Android phones, iPads, Web browsers and via email invitations.

Couples begin on AppyCouple.com, where a stylish, simple user interface walks them through seven steps for making their wedding app. Each app also comes with a wedding website that will display the same content for relatives or friends who don’t have smartphones.

One of my favorite parts about creating a wedding app was that I could change its design at any time. I started with a yellow-and-gray bubble design and later changed the design to a completely different black-and-gold pattern. With one click, the entire app was updated.

Another useful feature is the Events section. Only guests who are invited to certain events will see those events appear in their apps. So if only 15 friends are invited to the bachelorette party, only they—and not the rest of the guests—will see it. Couples can customize Events to add songs, guest polls, information on dress code, child care, weather, travel and hotels.

Appy Couple connects to Facebook, but only for the purpose of pulling images and names of friends into a section called Key People. It will never display any Appy Couple activity in your Facebook timeline. It also links to Yahoo, Google, Windows Live, AOL, Plaxo, Outlook and Apple’s Address Book for finding friends’ email addresses.

Judging from the many weddings I’ve attended, Appy Couple’s Gallery will be the most-used section on the app. In the test app I created, friends uploaded photos that can be viewed by the couple and other guests, and the app grew richer with their contributions. Images can be uploaded without pre-approval from the host couple, though any image can be deleted by the hosts on the AppyCouple.com website. A “moderation” option will be added to the app to give the couple more control over content.

A guest list can be uploaded to the app, but it must be saved as a CSV (comma separated values) file with columns for each guest’s first name, last name, email address and phone number. Couples who use traditional response cards will likely not also digitally invite guests to their wedding, but casual wedding events might merit a digital invitation.

Appy Couple’s CEO and co-founder, Sharmeen Mitha-Sehgal, wants couples to use personalized apps long after their wedding day. Next up is Appy Life, where people can create apps for events like births, birthdays, new homes and anniversaries.

This app brings useful wedding website content on the go with guests as they attend weddings. If nothing else, they’ll know how to get to the church and when the ceremony starts—even if they forget to bring the paper invitation.

Write to Katherine Boehret at katie.boehret@wsj.com

Write to Katherine Boehret at katie.boehret@wsj.com

Can I hook up my iPhone to my iMac and dictate into a word processor? Or should I just dictate into the Notes app on the iPhone and send that by email? I am executor of my mom’s estate and she left a lot of written memories that I want to compile into a book for family members. It would be a lot easier to dictate than to type them all.

A:

As far as I know, the iPhone can’t be used as a dictation appendage for a computer. You’d have to dictate into a document on the phone and transfer that to the computer. But you don’t have to use Apple’s Notes app.

There are many apps on iPhone and Android that can produce documents in Microsoft Word format which, when transferred to a PC or Mac, can be opened right in Word. Examples are Quickoffice, Documents To Go, and Apple’s own Pages. You can use dictation with all of these.

Q:

Enjoyed your article on using smartphones to turn dictation into text. I have recently become interested in various inexpensive devices that can record professors’ lectures into text. Do you think that the iPhone or Android phones can do that from a long distance, say, in back of the class?

A:

Anything is possible, but it’s not what the dictation features are designed to do, and I didn’t test that scenario. I doubt it would be very reliable or accurate.

The microphones on smartphones are typically designed to focus on a single voice close to the phone and to ignore the details of more distant sounds. It might work in a small, quiet seminar room with a professor whose voice is loud and clear, but I’m skeptical it would work in the back row of a large hall.

Email Walt at mossberg@wsj.com.

If you want a quick analysis of why Facebook would pay $1 billion for popular photo-sharing service Instagram, please ignore the obvious financials that just don’t add up at all and have most of the typically unshockable digerati shocked by the sheer amount of the price.

Actually, it’s pretty simple: Photos. Photos. And, oh yes, mobile photos — lots and lots and lots of them.

Astonishingly, Facebook users already upload an average of more than 250 million images daily, making it the most popular photo-sharing service on the Web.

But it’s not the best by far and not the most mobile, which is Facebook’s biggest weakness — that has been accomplished many others, especially Instagram, the favorite of power users who scoffed at Facebook’s weak tools. (The horror of no filters!)

Now — instead of all those billions of juicy digital photos snapped by an ever-growing legion of smartphone users loading up to the beautifully designed Instagram mobile app and living on the servers of the small San Francisco-based start-up — Facebook has now captured all these memories for its massive social networking site.

And while $1 billion seems an awful lot to pay for that privilege — Twitter is quaking with “OMG!” and “Wow!” and “WTF!” tweets about the acquisition — this is apparently priceless for Facebook in a deal that went down quickly and quietly in recent weeks.

That and the fact that the huge sum prevented Instagram from being scooped up by Google.

It’s a clear signal from CEO and co-founder Mark Zuckerberg — who rules all product efforts at the company — of his intent to dominate all innovations that have to do with owning the social experience.

Because while many Instagram photos quickly made their way onto Facebook — sharing on the service, as well as on Twitter, was a big part of the app’s offering — the future of the Menlo Park, Calif.-based company is tied to having control over key elements of the user experience.

Of all of those — communications, status updates, content linking — it has been photos that have become perhaps the most important part of Facebook, almost since its beginnings.

Photos are what allowed Facebook to grow so quickly and what made it more than just a blue sea of text and links to consumers. Its new Timeline depends on big, pretty photos, and Facebook even recently announced that it would allow full-screen viewing of high-resolution photos on its Web site, a pricey endeavor.

So, perhaps it was inevitable that Zuckerberg would pay up for Instagram, too — he knows a good entrepreneurial success when he sees one and apparently has the power to convince start-ups that he can make their bigger dreams come true.

Whether or not Instagram ever makes money is perhaps beside the point at this moment in time, as Facebook is poised to go public at 100 times the amount it forked over for Instagram.

But that it considers such a purchase worth as much as one percent of its expected valuation says a thousands words. And most of those words are “mobile” and “photo.”

As Ben Jacobs noted on Twitter: “Kodak goes bankrupt and Instagram is worth a billion dollars. 2012, y’all.”

Indeed. And, I have no doubt if Zuckerberg could figure out a way to shove all those Kodak moments from analog snapshots onto Facebook easily, he’d have paid up for that, too.

Facebook has just announced that it will acquire Instagram, the popular mobile photo-sharing service, for $1 billion in cash and shares.

The social networking giant posted on the acquisition, its biggest yet, on its site, as well as on CEO and co-founder Mark Zuckerberg’s Timeline on Facebook.

Photos are critically important for Facebook, which has been slow to innovate in the fast-growing mobile arena in the important consumer space. By contrast, Instagram has taken the arena by storm, with its delightful and elegant app and the motto, “Fast beautiful photo sharing.”

Consumers have responded (including me — it is the only non-communications app I use many times a day). The San Francisco-based company — with only 13 employees — had 30 million Apple iPhone users before it came to Google’s Android last week, where it got more than a million new users in just 12 hours.

Still, despite all the usage, Instagram had not articulated a plan for, you know, making money. Now, that will presumably be Facebook’s problem to solve.

The Facebook acquisition has been kept very quiet, with its CEO Kevin Systrom working on it in conjunction with new fundraising efforts that would have valued the company at $500 million. Liz Gannes reported on this effort last week, which was poised to close, in fact, before the Facebook deal was struck over the weekend.

Until now, Instagram has received Series A funding of $7 million led by Benchmark Capital just over a year ago, when it only had 1.75 million registered users.

Seed investors include Andreessen Horowitz — which did not follow on later — and Baseline Ventures. Also in the Benchmark round: Twitter creator Jack Dorsey, former Facebooker Adam D’Angelo and Chris Sacca.

In a blog post titled “Instagram + Facebook,” Systrom promised no change, except for the $1 billion mountain of cash:

“It’s important to be clear that Instagram is not going away. We’ll be working with Facebook to evolve Instagram and build the network … The Instagram app will still be the same one you know and love.”

Zuckerberg also promised that Facebook would keep Instagram independent, and that such a large purchase would be rare for the company, which is set to go public soon.

“This is an important milestone for Facebook because it’s the first time we’ve ever acquired a product and company with so many users,” he wrote. “We don’t plan on doing many more of these, if any at all.”

Here is the full press release from Facebook:

Facebook to Acquire Instagram

MENLO PARK, CALIF. — April 9, 2012 — Facebook announced today that it has reached an agreement to acquire Instagram, a fun, popular photo-sharing app for mobile devices.

The total consideration for San Francisco-based Instagram is approximately $1 billion in a combination of cash and shares of Facebook. The transaction, which is subject to customary closing conditions, is expected to close later this quarter.

Mark Zuckerberg, founder and CEO of Facebook, posted about the transaction on his Timeline:

I’m excited to share the news that we’ve agreed to acquire Instagram and that their talented team will be joining Facebook.

For years, we’ve focused on building the best experience for sharing photos with your friends and family. Now, we’ll be able to work even more closely with the Instagram team to also offer the best experiences for sharing beautiful mobile photos with people based on your interests.

We believe these are different experiences that complement each other. But in order to do this well, we need to be mindful about keeping and building on Instagram’s strengths and features rather than just trying to integrate everything into Facebook.

That’s why we’re committed to building and growing Instagram independently. Millions of people around the world love the Instagram app and the brand associated with it, and our goal is to help spread this app and brand to even more people.

We think the fact that Instagram is connected to other services beyond Facebook is an important part of the experience. We plan on keeping features like the ability to post to other social networks, the ability to not share your Instagrams on Facebook if you want, and the ability to have followers and follow people separately from your friends on Facebook.

These and many other features are important parts of the Instagram experience and we understand that. We will try to learn from Instagram’s experience to build similar features into our other products. At the same time, we will try to help Instagram continue to grow by using Facebook’s strong engineering team and infrastructure.

This is an important milestone for Facebook because it’s the first time we’ve ever acquired a product and company with so many users. We don’t plan on doing many more of these, if any at all. But providing the best photo sharing experience is one reason why so many people love Facebook and we knew it would be worth bringing these two companies together.

We’re looking forward to working with the Instagram team and to all of the great new experiences we’re going to be able to build together.

The thermostat, which works with an app on the iPhone, Android phone or desktop PC, now comes with an updated 10-day view of users’ energy consumption, called Energy History. On the thermostat itself, Nest users get a quick glimpse of their energy usage, but Energy History on mobile and the Web shows the exact times at which an HVAC system turned on and off, and how that compares to usage from previous weeks.

Nest also says it could save users money on air-conditioning bills this summer with something called Airwave, which shuts off a home’s air-conditioning system before the house hits its target temperature, then uses the remaining cool air in the system to finish cooling down the place. Nest says this will conserve up to 30 percent of air-conditioning energy.

The company shared some how-great-is-Nest stats: Nest thermostats are now installed in all 50 U.S. states; 99 percent of Nest users are running the thermostat on a setback schedule; and 75 percent of Nest buyers say they installed their thermostats themselves, in less than 30 minutes — pretty much all of those say they would do it themselves again.

Nest has also made minor adjustments to the backplate of the thermostat, after some customers complained the wall anchors weren’t working well. The connectors on the plate have been redesigned, and in the interest of even easier installation, the company has manufactured its own screws, which will be shipped with the thermostat.

Maxime Veron, Nest’s head of product marketing, said neither the hardware nor the software updates are related to a recent patent-infringement lawsuit filed against the start-up.

Nest, of course, is currently the target of a lawsuit filed by Honeywell, maker of aerospace systems, consumer products and technology solutions — and the creator of the now-iconic round thermostat. Honeywell has alleged that Nest’s digital thermostat, which came to market last fall for $249 (for a full review of how it works, check out my colleague Katie Boehret’s review here), infringes on seven patents Honeywell holds in home-thermostat technology.

Nest issued a quick statement to the suit a few days after the complaint was originally filed back in February, but got an extension to file a more detailed response, which is now due April 13.

All this over a thermostat? While some of Honeywell’s suit is focused on the design of the Nest thermostat, other parts of the complaint target the “smart” thermostat’s functionality. Part of Nest’s appeal is its promise to save users up to 30 percent off their utility bills, and many other Internet-connected, data-delivering home appliances are making similar claims.

For example, Honeywell’s complaint says that controlling a thermostat remotely through the Internet is not a Nest Labs innovation. The Nest thermometer comes with a patented “question system” — “What are the lowest and highest temperatures you’d like when you are away?” — but Honeywell says its Prestige thermostat, introduced in late 2008, also incorporates an “interview-based interface.” However, General Electric also markets a home-energy management system that includes the ability to remotely control a GE “smart” thermostat from a smartphone or home computer.

As more consumers warm to the idea of the connected home, it’s hard to imagine claims being made about the ability to control an appliance through the smartphone as a patented, innovative technology. But for now, we’ll have to wait until next week to see what Nest has to say about that.

Android users (on phones version 2.2 and higher) get almost the same features as iPhone users, with the exception of a few things like tilt-shift and blur.

On the occasion of the launch, Instagram released a bunch of stats:

• 430K+ on its Android waiting list
• 30 million+ registered users
• 1 billion+ photos uploaded
• 5 million+ photos per day
• 575 likes per second
• 81 comments per second

And now another social media app is introducing “Pinterest-like” boards: Timehop.

Timehop, in case you’e never used it, is a nifty social media aggregator that sends you daily emails to remind you exactly what you were doing a year ago today. Checked in on Foursquare at your favorite lunch spot? Timehop refreshes your memory. Tweeted that you were eating lunch? Timehop helps you recall that excitment, too. Instagrammed a picture of your lunch? Timehop reminds you of the time you treated your burrito as though it were an Annie Leibovitz subject.

Now when Timehop sends those daily emails, there will be an option for users to “favorite” certain posts and add them to a Pinterest-looking board on Timehop’s Web site. While these items can be added only through the daily email, this is Timehop’s first real Web feature. Until now, Timehop’s site has primarily just been a place for people to sign up for the service.

The boards right now are private, and users can only have one, which by default is called “Favorites.” Eventually, Timehop says it wants to allow people to have multiple boards and make their boards public to spur social interactions with friends online.

“Basically, we’re making Timehop more social and interactive and turning it from a purely consumption experience (read a daily email) into more of a place for social interactions on the Timehop website,” co-founder Jonathan Wegener said.

Formerly known as Foursquare and Seven Years Ago, and then PastPosts, Timehop first launched during Foursquare’s hackathon event last year. Like other social media apps — such as the maligned Girls Around Here app — Timehop aggregates all the data you’re sharing through other social media networks. But you have to give Timehop explicit permission to do so when you first sign up for the service, and until now the core of Timehop’s service was sending data through private email.

Timehop’s Wegener has also said in the past that the company might look to aggregate data from personal calendars to add value to the service, something that Greplin already does by culling and organizing user data from various mail accounts and calendars.

Last week, I visited Los Angeles to get a gander at some of the many digital companies that are doing some interesting things down south of Silicon Valley.

First stop: HipSwap, a community-based marketplace that is now in 14 U.S. cities after initial tests in Los Angeles and New York City.

Its goal is to de-creep the experience — because no matter how it’s done online, local buying and selling still has a lot of glitches. Using a visual approach (think Pinterest), with hipster social hooks (think Airbnb) and focusing on location (hmm, perhaps think Foursquare), complete with delivery in some cities, HipSwap is hoping to differentiate itself from big players in the space, such as Craigslist and eBay.

The app-heavy HipSwap allows anyone with stuff, including boutique merchants with quirky stuff to move, to quickly snap photos of items, price them and then — presumably — sell. Payment is made via PayPal or credit card, with HipSwap in between the buyer and seller, to ease the transaction’s typical awkwardness.

Because it is local, the items are varied, from trendy baby strollers to funky furniture to antique sewing machines. And, because it is in the L.A. area, HipSwap is also pushing celebrity fare, with a charitable “Shop My Closet” marketplace and video series, which recently included Kyle Richards from “The Real Housewives of Beverly Hills.”

The Santa Monica, Calif. start-up recently closed $1.1 million seed funding from a number of prominent investors, such as Founders Fund, Greycroft Partners, as well as former Microsoft exec — and early Pinterest angel — Hank Vigil and Mahalo President Jason Rapp.

Here’s a video interview I did with co-founder and CEO Rob Kramer about the interesting retail concept: