I think that the idea of social media networks being closed areas is going to change over time as it did with AOL's walled garden approach etc.
charlene Li of Forrester has some very interesting thoughts on this. The problem is it is such a pain having to develop different passwords etc to enter each social media network. What could emerge is open social media network tools.
http://blogs.forrester.com/charleneli/2008/03/the-future-of-s.html
