We just finished watching the livestream of Facebook’s “Places” announcement.

Here are our initial impressions:

Facebook will now become the platform on which other check-in applications like Foursquare will be built. This puts Facebook in an even more powerful position than it is already in.  If Facebook’s check-in functionality takes hold as the world’s default check-in engine, there’s a chance that much of the mobile application world will incorporate its API.  And that can only be good for the company.

Google is nowhere in the social game–and its chances of getting somewhere diminish every day. Android won’t help Google here.  Being the platform that runs the device on which the Facebook mobile app runs is not as powerful a position as providing the social graph that enables social apps to function–independent of the devices on which they are used. (Microsoft, meanwhile, is so absent here that it doesn’t even warrant a mention).

Foursquare, Gowalla, and other pioneers in the check-in business are now likely to become ancillary applications with more limited appeal. This doesn’t mean they’re toast (especially Foursquare)–just that they now have narrower opportunities.  “Mayorships” and “badges” and other gaming elements of Foursquare’s app are likely to appeal to a smaller community than Facebook’s “what your friends did, said, and ate here.”  As an analogy, everyone uses Facebook; fewer people play Farmville (but Zynga’s hardly a hurting company).

Twitter really isn’t playing in the location game. And, despite a lot of talk, it probably won’t play aggressively in it–at least not in the one Facebook is going after.  Why not? Because Twitter also isn’t really playing in the “friend” or social space.  Twitter has become a sort of an interactive, personalized talk radio, a way to interact with and listen to a wide circle of people that extends way beyond friends.  It’s very useful, and it’s here to stay (Facebook won’t kill it), but it’s not really about location.

The press conference and demo really brought home how different mobile social apps are likely to be than PC-based social web apps–as well as what is likely to happen over the next few years. These apps are as different as web services were to packaged PC software.  And as Facebook’s Chris Cox suggested, they will likely radically change the way people behave and interact in the real world.

Now, there’s always a chance that Facebook “Places” will go the way of Google Buzz… a product that generated a lot of excitement right out of the gate, and then flopped.

Buzz’s flop was not for lack of effort or talent on the part of its development team. Buzz flopped because it was (and is) a minor product at Google, far from the company’s core competence, and far outside its comfort zone.  “Places” could suffer the same fate, but it already appears to be much more central to Facebook’s product and mission than Buzz is to Google’s. So we suspect that, after the usual bumpy roll-out period, Places will be here to stay.

One final observation: We thought Facebook and Mark Zuckerberg were at the top of their games tonight.  Mark was relaxed and in his element, and after a couple of challenging and awkward public appearances recently, seeing him in his element was refreshing.  Facebook, meanwhile, is positively bursting with excitement and energy, as might be expected of a company that has wrested the center-of-innovation mantle from Google and is really, truly changing the world.

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