Big Brother
Hmmm, I think Google have the right idea on a social network that allows you to profile different kind of friends- FB is utterly retarded in that regard although they have tried to improve it. You need to be able to have seperate relationship types and allow a single person to have MULTIPLE labels- i.e. friend and work colleague. The trick is to automatically profile content such as photos correctly so your work and social friends don't see the same tagged photos/wall posts and so forth. If they can get that right it will be awesome.
On the other hand I hope it DOESN'T take off as I am already too dependant on Google for many things and I don't like one company getting to be too dominant. At some point it could go bad, its really tough for such a large corporation not to. It most likely will not be intentional, but the combination of all your search, communications, social interactions, geographic locations and so forth all through one company is not ideal. Add operating system and applications (browser) and it starts getting a little worrying.