Plenty of other people are commenting on this, so I might as well join in. Google have released what seems to be essentially a 3D chatroom environment. I’m guessing that the folks at Google are making use of their software portfolio, so this is probably some sort of visual wrapper round XMPP, as used for Google Talk. The 3D design of the rooms looks as if it hails from the approach used in SketchUp, so I would not be at all surprised if some sort of integration with Google Earth were to come along in a while and add a geolocation aspect to this system.
What it most definately is not (at least right now) is a central collaborative environment in the vein of Second Life or World of Warcraft.