I can attest to the great difficulty in getting people to buy into using a social network, although my situation may be different, since I am on a small university campus.

As far as I can tell, none of theses social networking platforms are specifically targeted at educational institutions, although from what I can gather on the web, a few universities are giving them a try. There is no shortage of silos on university campuses.

I am not aware of the pros and cons of various platforms, (eg yammer versus socialcast) in terms of utility for educational institutions.

It would be nice if someone started thinking about social networks on campus and how they might be more effectively designed and used for that market, although perhaps that is too small market?

In any event, I think you might need a somewhat different cookbook of ideas to help establish social networks among academics.