Interesting article from Clay Shirky on the sociology of on-line groups. It's a little old now, 2003, but still good for all that.
As a collective, we have long been interested in this topic for two reasons. Some of us consult in the area and hence are interested for professional reasons. Then, too, we have tried to us the technology to keep our own distributed network in contact.
The second has been less successful than the first. The reasons are simple. While a fair bit of the new social networking technology aims to facilitate and support the creation of groups, we are already one. So the technology has to fit into existing structures, group dynamics and processes. And here it does not work as well.
A core reason for this is that our people judge the technology in terms of its immediate contribution to their personal and professional objectives in a Group context. Here they judge the time taken to learn to use the technology plus the time taken then to use it against the returns. And too much technology fails this very basic test.