Video sites branch out.

Okay, that's an exaggeration. 

But a good article here on, how easy it is to set up a blog community, and then the inevitable questions regarding how to manage membership in multiple communities.

The quote: 

Any whoozit with a hundred bucks can install an elgg or a drupal or a moodle or a wiki and spam the bloggosphere saying that “this is the new community… supporting (insert obscure bit of cartilage on the long tail here)” We are increasingly collaborative, increasingly involved in collaboration… We are members of our banking sites, our research sites our community sites our schools our communities of practice…