The SFGate has an decent intro to video blogs:

In less than two years, the number of video blogs, also known as vlogs and video podcasts, has exploded from a handful to more than 7,000, according to video blogging directory Mefeedia. “It’s Jerry Time!” — which consists by a single, fortysomething man’s rants on life — was even nominated for a special Emmy award this year, although it lost to an AOL production. And next month, hundreds of vloggers from around the world plan to converge in San Francisco for a conference dubbed Vloggercon.