To my knowledge, only one! And she tends not to update for long stretches.
Plus, she's young -- 26. People in the next generation up, I find, still tend to say "I don't do computers" like it's a moral thing.
I know a couple who blog. A lot of older people are into computers around here including me and my mom. I'm 43 and she's 63 but I know what Nancy means about the "I don't do computers." comments. I think some people are just scared to try.
I know around 7 or 8 people who blog, but a couple of those I've only met once or twice in real life. I've inspired at least 3 people to start their own blogs, either directly or indirectly. Such a cool feeling! :)
I had to stop counting when I got to 40. A lot of the folks are friends and family who live far away, so it is a great way to stay in touch. Not everyone updates regularly, but I have them in my Google Reader so I know when they do!
I've also met people whose blogs I read before meeting them. That is always a lot of fun.