What a stupid idea, dj bill! JUST KIDDING

I think Stewart's point was, if you want something that works like a blog, why not just use a blog system? The open-source Wordpress is free, very easy to use, and supports multiple users.
Now, I too have considered creating a blog-like system from phpBB. There are reasons you may want to do something like this. For example, if you have a community site that has a forum, and you also want to give people blogs, you don't want two seperate systems or two seperate authentication databases. No, you want a single login for your whole system. Of course, there are ways to integrate logins between different systems, but it's always a messy hack.
I think you are correct--I think dani has heavily modified vBulletin to do some really cool stuff. For example, the daniweb blogs.
I haven't thought the whole process through yet, but at least with phpBB, I don't think it would really be that big a deal. You can already create threads that are locked to posts except from the moderator. That "moderator" could be the blog author. You'd probably want to modify the page that spits out a thread to remove the author's name from being displayed for every post since you know the entire blog is one person. I think you'd hack a system where you'd create a thread, assign a moderator account to it, and lock the thread so only the moderator can post. Then you assign a single thread as the "comment thread" to the blog thread. Definitely would take some hacking, but not rocket science for sure.
Maybe csgal will respond. She definitely has experience with this subject.