In an interview with Evan Williams, the prime mover behind Blogger, he made the following comment about how weblogs differ from other kinds of online communities.
“The difference I see between informally linked blogs and other sorts of online communities, is that when people have their own space to write and express themselves, as opposed to some sort of shared space, they feel a lot more ownership and freedom in that space. This encourages more of themselves to show through, which I think can actually result in a stronger community than something that is more structurally linked. We’ve recently done some licensing deals that we hope will create this same effect within other sites.”
You can read the entire interview here: Online Community Report