In response to a request from Campus Activities here at NC State, I am currently researching different products that could be used for university-sponsored online social networks. I had hoped that the Libraries here at State were developing something on this front (as they have for wikis and blogs) but no such luck. (I can see where this actually is outside the realm of the Libraries, but it never hurts to hope!) Nothing like this going on out of ITD, and I still need to check with DELTA.
I’ve played around with Ning, and there are certainly others, and I’ve found one review (so far) of several products. However, providing such a tool is fraught with all sorts of problems: accessibility, privacy, and so on. Some colleagues at the University of Minnesota are engaged in a similar project so I hope to get some good ideas from them.