This link (tympan) is a blog post that demonstrates community built by blogging. There are a number of poetry bloggers who all read and refer to each other's blogs (if not poetry). This particular post is one of many about Ron Silliman's recent reading in Oakland. If you read iit you will learn that these poet bloggers all know each other, but have never met. You'll also be able to immediately tap into there discourse community through in-post links and blogrolls.