I'm working on that, although I haven't coded it for some time, but for next year we got a project that will sponsor community features development.
I'm happy to see other people interested. Currently there's not much about being friend of other people, but for next months we'll be working on peer-review, communities (based on group, check UserPagemarclaporte on some ideas about groups, that's probably the way we're going) and karma system.
You can contribute by giving ideas, testing, if you can code be free to implement your ideas
Luis aka batawata