This is an interesting story on the social networks for MMO's. I happened across it today and you should take a look. You can read it all right here.
I just finished reading the awesome + amazing work of Nicolas Ducheneaut, Nicholas Yee, Eric Nickell, and Robert J. Moore. I imagine them as hyper-dorks at Stanford who built a scraper for analyzing social behaviors in World of Warcraft... only they got a little too high off of their MMORPG supply.
Just kidding. About the high part. They really did build a WoW scraper.
Their paper, "Alone Together?" Exploring the Social Dynamics of Massively Multiplayer Online Games (pdf) blew brain chunks out the back of my skull.
I've only read it through once, but came away feeling strongly that social networks, as they exist now, will soon be relics as new networks emerge that provide reward systems to enhance user experience with tools and recognition.
(also the paper made me wonder if social networks will become more immersive as well... is Second Life the future of social networks?).
As a social network hobbyist I recognize that this concept could exist in practice already. Forgive me if it's been done and be sure to point me to where and by whom.
On a side note... WoW is surely the worst game to study social networks considering there aren't any. Have you tried socializing on a mature level in that game lately?