The Venice Biennale has a blog. I think that it's kinda cool, but at the same time, there's more than a bit of blog overload. I mean, actors have blogs, writers have blogs, presidential candidates have blogs...
Next thing you know, cats will start blogging. Oh, wait, nevermind...
Apparently you haven't spend enough time looking on LJ. That weblog you linked to was a blog about cats. There are online journals by cats.
Incidentally, I hate the term "blog". :P Weblog, Journal, whatever. Blog, hiss, boo.
that is, of course, if you consider wil wheaton an "actor".