I read a lot of blogs (I use Bloglines to aggregate). Most of them are professional blogs about junk that I care about. A few are personal as well.
Catherine asked me a couple of weeks ago why I blog, and I told her that my motivation included several reasons. First is that I like to share with people. I have a comfort level with what's generally OK for other people to know, and I keep the rest among friends, verbally. The second is that it's therapeutic for me. Just typing something out, knowing someone else should be able to understand it, helps me better understand it myself. For me at least, I try not to be too narcissistic, as the audience is not critical to what I decide to write about.
That said, blogging has the enormous power to make "famous" people completely human as well. Robert Scoble is a Microsoft developer evangelist. He promotes the tools and platform to developers and makes sure they have what they need to succeed. He's also a very prominent blogger because he was really the first to break out of the "approved" PR shell of Microsoft. He very openly criticizes his own company, and everyone right up through Bill Gates knows it.
Scoble's mother had a stroke following heart failure. She's in bad shape, and he described the situation in a fair amount of detail on his blog. Posts before and after go into additional detail.
Certainly this is tragic for him and his family, as they now essentially have to watch their mother die, but as an outside observer, it also reminds us of the humanity of "celebrities" on the Internet. They are indeed real people, and the stuff they blog about is likely only a fraction of what their lives are really about.
Something to keep in mind when you're reading a blog. You're probably only seeing a small fraction of what the author is really about.