Social Circles – Venn map, originally uploaded by densitydesign.

Brad Firzpatrick recently wrote an elegant and important post about the Social Graph, a term used by Facebook to describe their social network In his post, Fitzpatrick defines “social graph” as “the global mapping of everybody and how they’re related”. He went on to outline the problems with it, as well as a broad set of goals going forward…

Full article avaible here:
Social Graph: Concepts and Issues, by Alex Iskold