I spoke about this a bit @ SourceCon, but today it is actually happening. Facebook has made such an impact in Social Networking (SN) that Google has convinced a slew of other smaller SN's that Google is their friend and they will help the smaller guys compete against Facebook. Ironically, the exact opposite is true - Google needs help against Facebook.
All that being said, I think Social Graphs are a good idea and will be enormously helpful to recruiters. Think of a social graph as a way of allowing users to network socially outside the walls of a social network. In essence a set of standards that will connect ALL social networks.
RecruitingBlogs.com was founded in 2007 and is the social network for recruiters and HR professionals with over 35,000 members and over 21,000 blog posts and forum discussions. Its global online network provides recruiters with a forum to share, interact and collaborate with one another.