I think that's a very good characterization of them, Oliver. The networks amongst people that arise thanks to enabling technologies (Blogger, Blogdex yadda yadda etc etc), and the transient conversations (like this little one here) that flare up and burn out over the matter of a few days, are completely ad-hoc. That's a strength, I think. It's easy to start a blog, and even easier to just drop in to a comment thread and contribure your thoughts, whether you're a person who has some flavour of weblog or not, whether you count yourself part of any tribe(s) or not...