I really need to read the book first - so I learn about the first 3 types of blogs.  Seth Godin has come up with 4th type of blog that is used to keep and solidify a Fan Base - could be movie, or a performer - or an idea.   It’s what the blog is used for that makes it the 4th type of blog.

"In my free ebook about blogs (Who’s There?) I write about three kinds of blogs: cat blogs, boss blogs and blogs designed to spread ideas. Shame on me, I left out a fourth kind, a kind that is growing in popularity and influence."

"…..These are blogs with a posse, a cadre of loyal readers who participate by chat, comments or in a tightly-knit circle of blogs. The goal of the blogger is to put fuel on the fire and to keep the existing audience engaged. The ideas don’t have to be new, and they don’t have to spread, but the blog is a great way to create and maintain this community of fellow travelers".

I’m not sure that’s a good or bad thing - it seems like the logical extension of living more and more in cyberspace where your community of friends might be people you’ve net met and probably never will meet, but are still intimate with, in a way.   To keep that going - a blog of the 4th type is needed, and that’s what Seth noticed, I think.