Caterina Fake has written an excellent commentary on the social evolution of online communities. For those who don’t know her, she co-founded flickr and has been involved in a lot of behind the scenes work in many online communities.
I’ve been involved with many online communities over many years as well and am still involved with many, some big, some small collections of people who hang out in comment threads. There’s something about this kind of connection that works for me, even with the issues of trolls and such. The fact that people are connecting is simply astounding to me and I’ve never taken it for granted.