I don't think there are sites that do this currently, but the idea is definitely in the air, so there are probably guys working on it. For example, it seemed something like 3 of the 5 guys from the Google IO VC panel from late last week talked about wanting to fund collaborative educational startups.

EDIT: This is the panel I was talking about ... http://news.ycombinator.com/item?id=1405320

Unclasses.com allows people passionate about learning to connect. Not sure if anyone has started an MIT thread, but that might be a community of learners that would be interested in collaborating together.