ReelBlogs just launched today, and is the first video blog network ever on the Internet. From the home page:

"“There is a rapidly growing demand for good video content online, but no one is producing it yet,” said Robert Spiro, one of the founders of ReelBlogs. “ReelBlogs will use the self-publishing model of blogs to distribute exciting new video serials.”

Other blog networks of note are 9rules, Weblogs, Inc, b5media, and Gawker Media.