I don't know anything about that (I don't like blogs

), but what is it really?
A system that lets you post pages that visitors may comment on (and perhaps rate)?
That's really easy to make. If you know programming, you'll get php in one or two days (the basics at least, and there's great references over at [href]www.w3schools.org[/href]). It's c-styled syntax and has built-in core features that makes it easy to communicate with a sql database.
For guestbooks, it's basically the same thing.
I'd say give it a shot at doing it yourself - it's pretty intriguing in my opinion and knowing a server-side script language is always good. Just ask if you've got any questions