From the Blogger Knowledge Base: How To Get A Book Deal With Your Blog. They leave out Julie Powell, though perhaps that's because she was using Radio...
Update: OK, as eagle-eyed reader and official cousin of pf.org Nick Tang points out, they actually included Julie. My bad. Perhaps I should actually read things before I post them.
Uh, no they didn't... :)
"Julie Powell managed to swing her abnormal behavior into a book deal too. Down on her luck as a secretary in Queens, NY, Julie said "screw this!" (in her own way) and decided to blog-u-ment her crazy scheme to cook more than 500 Julia Child recipes in one year. Her blogging struck a chord with readers and heavy commenting on her posts was not unusual. The activity around her blog lead to some media coverage, and she soon found herself signing a "really obscene book deal" with Little, Brown and Company. Look for her book in stores early 2005."