At the St. Regis hotel in San Francisco, Mark Zuckerberg says young people say email is too slow. They prefer Facebook or SMS.

Zuck: IM or SMS are much simpler, and people want lighter-weight things that they can use all over the place. So we need…a modern messaging system.

350 million people actively use messaging on Facebook, in part because it’s really simple. Four billion messages are sent per day. This is “private, private sharing.”

Next-generation messaging would be: seamless, informal, immediate, personal, simple, minimal and short. (Those are a lot of synonyms, no?)

“This is not email. Email is one way that people will use this system, but it’s not even the primary way we think they will use it.”

Now a three-panel slide is up showing the key topics of the announcement–”seamless messaging,” “conversation history” and “social inbox.” Zuckerberg promises, “We can do some really good filtering for you to make sure you only see messages you really care about.”

Zuck brings on Andrew Bosworth to demo the product.

So this is actually a relaunch of the “Messages” tool. Not email-specific. Takes all correspondence between two friends and puts them in one place.

Everyone gets an @facebook.com email address with their username. “As much as we’re providing an email address, the system’s not email,” says Boz–more like instant messaging.

Boz uses convo about dinner plans as an example, with messaging across different platforms, including IM on Facebook, email, iPhone notifications, etc. The example restaurant is Piccino in San Francisco, where, fun fact, I was for a short time the Foursquare mayor. No longer though.

Integrates with Jabber, IMAP and one more I missed. (Sorry, first time liveblogging with this tool!)

Boz shows the history of Facebook messages with his girlfriend of the last four years. But doesn’t include their instant messages and other communication. Individual messages may not be profound, but collectively they provide a narrative about someone I care about, says Boz.

Facebook rebuilt infrastructure for this project, because it’s especially important that messages don’t get lost.

Instead of Cassandra (which FB created for email search and then open sourced), the company chose something new: HBase. They also used Haystack, Thrift, ZooKeeper and memcache.

This is the biggest engineering team Facebook has ever put together for a launch–15 people, Boz says.

Users have three categories: 1) Messages: Conversations with actual people. 2) Other: Email lists and the like. And 3) Junk.

The big idea is “picking up where you left off” no matter what device or medium.

This project has been in the works for the last 15 months.

Zuck: “This is not an email killer. This is a messaging system that includes email as a part of it. We don’t expect anyone to wake up tomorrow and say, I’m going to shut down my Yahoo account or my Gmail account and switch to Facebook.”

(Read: You silly press, we’re not competing with Gmail, we’re bigger than Gmail!)

Rolling out slowly over the next few months, starting with an invite system (ha! how Gmail!).

Oh, about IMAP: No support yet, so users can’t synch with other email systems. But Facebook wants to add later.

Interesting: Facebook messages won’t have subject lines. You just have a single messaging history with each person.

If you have been interacting with someone through email, then we’ll send replies back to email. You can indicate that you want a message to go directly to their phone. If you’re online, you get a message as an IM.

Boz: This is the end of “BRB” or “GTG.” Follows you wherever you go. (Sounds ominous when you say it like that.)

Question from audience: Will you add voice or video?

Zuck: For now only SMS, IM, email and FB messages–all are text. “We think this is a pretty big step by itself, and one we just wanted to take before we get started on the next set of things.”

Question from audience: Will you have contextual ads?

Zuck: Yes, ads work the same as on the rest of Facebook, but not targeted specific to content in a message.

Zuck on Gmail competition: “They have a great product. Email is still really important to a lot of people. If we build a great product that people want to use, then people will use it.”

Question from audience: Can users go off the record like in Gmail?

Boz: Users can delete any message.

Zuck: Off the record like in IM doesn’t make sense because users may be receiving messages in a different way than you send them. If someone gets something in email instead of IM it would be unnatural to have it off the record.

Question: How will this treat communication with people who are not on Facebook?

Boz: You can communicate with whoever you want to, and will have access to all that history of the conversation.

Zuck: If you’re not a part of the FB system and outside the social graph, your emails to FB users will go into “Other” folder to start off with, rather than the main. Once the recipient says you’re an important person, you’ll go into the main folder.

Question: What about silly joke emails from your mom? Can you filter those?

Zuck: There’s only one thread with every person.

Question: What about Facebook employee email addresses?

Zuck: “After a long discussion, the Farm Bureau has agreed to give us fb.com. And in the terms of that we have agreed not to sell farm subsidies.”

Facebook hasn’t mentioned this, but Microsoft just emailed to make sure people know they’re involved.

“As part of Facebook’s new messaging system: http://apps.facebook.com/facebooklive/ –Microsoft is integrating the Office experience. Over the coming months, customers will be able to access and share Microsoft Word, Excel and PowerPoint documents as attachments to their Facebook messages. Sharing new ideas, key points of inspiration and important information just got easier–even when the need to access or share that content strikes in the middle of your latest status update.”

Question: Can you fill in the blanks of associating email addresses with Facebook friends?

Boz: Not yet, but it’s imaginable.

(Uh-oh–how is this going to work when people have multiple contacts for themselves?)

Question: Storage?

“If you’re a good user, you have no concern. For people who try to find limits, they will find them.” Another ominous comment from Boz.

Okay, they’re cutting us off.

Here’s the Facebook blog post on the announcement.

Please see the disclosure about Facebook in my ethics statement.

At least one smartphone manufacturer is doing something about this. This week, Research In Motion (RIMM) introduced the BlackBerry Pearl Flip 8220, available for $150 with a two-year contract from T-Mobile (DT). This device is the first BlackBerry in a flip phone, or clamshell, form. Like RIM’s mainstream, candy-bar-shaped BlackBerry Pearl, the Flip uses a SureType keyboard, which has condensed keys and relies on predictive text software.

The Pearl Flip uses a SureType keyboard, which takes up less space.

After using the Pearl Flip for a week, I’ve found it to be a stylish messaging device that works well as a comfortable phone. I really liked its exterior screen, which is designed to show previews of incoming messages, saving people the trouble of flipping open the device. It runs on T-Mobile’s slow EDGE network, but has built-in Wi-Fi and the ability to automatically connect to saved, nearby wireless networks.

First-time smartphone buyers will likely find the Pearl Flip to be a good fit. When it flips open, a special hinge drops the top half of the device slightly behind the bottom half, and a handy trackball makes navigation easy. The Flip’s Web browser enables streaming videos that look sharp on its interior screen, and a microSD card slot supports up to 16 gigabytes of memory.

But current BlackBerry owners who want to switch to a device with a more comfortable phone may have trouble adjusting to the Pearl Flip’s SureType keyboard — especially if they’re used to a device with a full QWERTY keyboard. Though the Pearl Flip’s keyboard is a generous size and its keys are flat and easy to press, its SureType design assigns two letters to almost every key, which can be frustrating to use when predictive text guesses a different word than that which is intended.

The Pearl Flip 8220 is RIM’s first flip phone BlackBerry.

The Pearl Flip supports T-Mobile’s Unlimited HotSpot Calling, a service that doesn’t use any minutes on phone calls begun in Wi-Fi zones. Even if a user leaves the Wi-Fi zone in which he or she started a phone conversation, the call passes over to the T-Mobile cellular network without dropping out. This service costs $10 monthly in addition to regular service charges.

When I made calls on the Pearl Flip, friends on the other line noted how crisp and clear our connection sounded. And best of all, the Pearl Flip’s long, clamshell profile was easy to hold and fit snugly and comfortably between my ear and shoulder when I needed two hands to carry things.

BlackBerry’s signature red light blinks in this device’s top corner to indicate new messages. The 1.6-inch exterior screen displays about 25 words (give or take) from newly received emails, instant messages, SMS, MMS, calendar notifications and task reminders. If a message is received from a contact to whom a photo is assigned, that photo also shows up on the external screen to identify the sender. Side buttons let users scroll up or down through these previews.

This display is designed so that the same message being previewed externally will appear on the internal screen as soon as the Pearl Flip is opened. This makes sense because people will want to reply to some emails or read their entire contents after seeing a short preview. But my device didn’t do this at first; instead, the internal screen seemed completely unrelated to the external screen. I finally got this feature to work after my external screen froze and I rebooted the Pearl Flip. RIM said it hadn’t seen this behavior before, and wasn’t sure what had caused it.

The interior screen measures 2.4 inches diagonally and has a resolution of 240×320 pixels, which is a larger, higher resolution screen than most basic cellphones. While using Wi-Fi, I pulled up YouTube.com and watched a video. It played without skipping or stopping while streaming directly from the Web. A higher-resolution video, which was saved to my device, automatically played in horizontal mode so as to take up the entire screen; YouTube videos play vertically, without using the full screen.

Up to 10 email accounts can be set up on the Pearl Flip; I had no problems using Hotmail, .Mac and Gmail accounts. I also signed into AOL Instant Messenger and Google Talk on the Pearl Flip. Along with these messaging programs, ICQ, Windows Live Messenger, Yahoo Messenger and BlackBerry Messenger also come pre-installed and ready to use.

If my Pearl Flip was closed and I remained signed into an instant-messaging client, notifications appeared on the external screen telling me who was sending an IM and what it said. When I opened the device, I was automatically directed to the screen where I could reply to the instant message.

I tested the T-Mobile Unlimited HotSpot Calling feature by starting calls using a Wi-Fi network and then leaving the network’s range. The calls remained steady without dropping or fading, and if I were a paying customer, I wouldn’t have been charged minutes for those calls. Calls that start out of Wi-Fi zones and end in Wi-Fi zones do deduct minutes. My Pearl Flip had no trouble automatically moving from the cellular network to a Wi-Fi network.

All T-Mobile Wi-Fi hotspots, such as at airports or in Starbucks (SBUX), automatically work with the Pearl Flip if you’re registered for the $10 monthly Unlimited Hotspot Calling.

If you’re considering taking the plunge into the always-connected world of smartphones, or if you want a more comfortable phone in your smartphone and don’t mind the quirks of SureType, the Pearl Flip 8220 may be the BlackBerry for you.

– Edited by Walter S. Mossberg

• Email us at mossbergsolution@wsj.com. Find this and other columns and videos online free at the All Things Digital Web site: http://walt.allthingsd.com