The app is notable because it was created by Jyri Engeström, who previously founded Jaiku, a Twitter competitor that Google bought in 2007. Engeström was then Google’s “head of social,” but left dissatisfied in 2009. Pieces of the never-released product he’d been developing at Google showed up in Google Buzz, Profiles and Latitude, according to Engeström.

Engeström, a sociologist by training, said the rise of the mobile touchscreen was part of what brought him back to the game, because he thinks he can create a meaningful and fun experience without requiring users to do much typing.

Ditto users press big colorful buttons to indicate what they want to do–for instance, eat out. Then a user receives recommendations for nearby restaurants directly from friends but also from processing friends’ historical check-in data. That seems similar to Foursquare, but Engeström said it’s more useful, because users turn to Ditto before they make a decision about where to go or what to do. In that way, it’s a bit more like a social Q&A service.

The current Ditto app also supports movie recommendations, and will add other categories like books and music, with the idea that a user could consume recommended content directly on the phone from Netflix, Spotify or Kindle. Engeström also said the company will develop for Android next.

This horizontal approach to discovery will likely be hard to pull off, because users with app-filled smartphones aren’t sitting around waiting for the perfect all-purpose social recommendations app.

So if attracting users does prove to be hard, would Engeström sell out, given his negative experience with Google? What about in the context of Beluga, the group messaging app that already sold out to Facebook this week, before its inevitable larger competitor had even launched anything like it?

Engeström said one advantage he has over Beluga (whose founders worked for and with him at Google) is that recommendations are monetizable through advertising and affiliate relationships–whereas SMS costs money and doesn’t have an obvious business model. He also attested that Ditto has already had acquisition inquiries before it even launched.

Ditto has raised $775,000 from Betaworks and True Ventures, and has a team of three based in San Francisco.

“How much do you think we would sell Android for today?” Lawee recently asked Reuters. “I would argue it would be in the billions and billions of dollars, it’s worth a lot of money. The same of YouTube.”

Of course those are just two acquisitions out of the 80 or so that Google’s made since 2001. Which is not to say that there isn’t another Android or YouTube on that list, just that “paying off huge” isn’t the way one would describe Google’s purchase of, say, Jaiku or DodgeBall or the five percent equity stake it took in AOL (AOL).

But obviously the threat of a clunker investment or two isn’t going to temper Google’s aggressive acquisition strategy. Back in January, CEO Eric Schmidt predicted the company would make one acquisition a month. With a little over three months left in the year, Google (GOOG) has made 23, nearly double Schmidt’s forecast.

The search giant made a series of cuts yesterday: It fired 100 of its recruiters and announced it was shutting down a handful of its many side projects.

None of these moves means much on their own: Google (GOOG) still has some 20,000 employees, and some of the 100 HR folks it is cutting may find jobs somewhere else in the company. And you’ll be hard-pressed to find many Google users who are outraged about the stuff the company is pulling the plug on.

Jaiku, for instance, is a would-be Twitter competitor with no traction. And I know one person who professes to still use Dodgeball, a mobile/social service that seemed like a big deal in 2005, but never took off.

And if you’re determined to look on the bright side, you can view the cuts as a good thing: Wall Street has been begging Google to slow its hiring for at least a year. And even prior to last fall’s announcement that Google would be cutting “dark matter” projects that “haven’t really caught on” and “aren’t really that exciting,” CEO Eric Schmidt had been talking about refocusing on search.

The flip side: The layoffs are layoffs, and they are the first-ever at Google, which has only experienced growth in its 10-year history. And since the cuts are in the recruiting group, you can expect hiring to slow to a crawl. (Anyone apply for any of these jobs recently? Let me know how that went.) And if Google isn’t hiring, who is?

In late September Google purchased mobile social-networking start-up Zingku. Now it’s gone and bought Jaiku, a Finnish company that offers an “activity stream and presence-sharing service” similar to the more widely known Twitter. Two months. Two mobile social-networking start-ups. Google never explained its plans for Zingku. What’s it going to do with Jaiku? Who knows …

“We plan to use the ideas and technology behind Jaiku to make compelling and useful products,” product manager Tony Hsieh wrote in a post to Google’s corporate blog this afternoon. “Although we don’t have definite plans to announce at this time, we’re excited about helping drive the next round of developments in Web and mobile technology.”

Ah. Helping to drive them the way you drove Dodgeball? To that happy place where social-networking apps go to die? Kidding, of course.

Anyway … Why did Google choose Jaiku over Twitter, a similar company with far greater brand recognition? “The answer seems pretty obvious to me,” says Tim O’ Reilly. “Jaiku isn’t a ‘lifestreaming’ company per se. They are a mobile company in the business of creating smarter presence applications. Far from being a runner-up behind Twitter, they are a leader in a category most people haven’t fully grasped yet. Google is clearly thinking a lot about mobile, and so they do grasp it.”

Of course, there’s another answer to that question as well. Twitter founder Evan Williams, whose previous company, Blogger, was acquired by Google in February 2003, may not have wanted to see another of his creations doomed to irrelevance by the search giant.

Which is not to say Twitter won’t be acquired. As RedMonk analyst James Governor points out, the company is probably looking pretty good to Yahoo right now. “Google and Yahoo are in dueling acquisition mode, and Yahoo is almost certain to respond,” said Governor. “Especially since Twitter has begun to use a footer on SMS messages it sends out–which could of course be used as a microbillboard.”

In late September Google purchased mobile social-networking start-up Zingku. Now it’s gone and bought Jaiku, a Finnish company that offers an “activity stream and presence-sharing service” similar to the more widely known Twitter. Two months. Two mobile social-networking start-ups. Google never explained its plans for Zingku. What’s it going to do with Jaiku? Who knows …

“We plan to use the ideas and technology behind Jaiku to make compelling and useful products,” product manager Tony Hsieh wrote in a post to Google’s corporate blog this afternoon. “Although we don’t have definite plans to announce at this time, we’re excited about helping drive the next round of developments in Web and mobile technology.”

Ah. Helping to drive them the way you drove Dodgeball? To that happy place where social-networking apps go to die? Kidding, of course.

Anyway … Why did Google choose Jaiku over Twitter, a similar company with far greater brand recognition? “The answer seems pretty obvious to me,” says Tim O’ Reilly. “Jaiku isn’t a ‘lifestreaming’ company per se. They are a mobile company in the business of creating smarter presence applications. Far from being a runner-up behind Twitter, they are a leader in a category most people haven’t fully grasped yet. Google is clearly thinking a lot about mobile, and so they do grasp it.”

Of course, there’s another answer to that question as well. Twitter founder Evan Williams, whose previous company, Blogger, was acquired by Google in February 2003, may not have wanted to see another of his creations doomed to irrelevance by the search giant.

Which is not to say Twitter won’t be acquired. As RedMonk analyst James Governor points out, the company is probably looking pretty good to Yahoo right now. “Google and Yahoo are in dueling acquisition mode, and Yahoo is almost certain to respond,” said Governor. “Especially since Twitter has begun to use a footer on SMS messages it sends out–which could of course be used as a microbillboard.”