From Dave Winer on his Harvard Blog site: What Makes a Weblog a Weblog? Dave is a Harvard Fellow teaching weblogs. He was also a prime mover and shaker behind various weblog technologies and major products like Manila and Radio.
To me, a weblog is a simple way to publish words to a worldwide audience. Publishing was always the fifth part of the Writing Process, and now it’s attainable without having to enter Scholastic writing competitions or submit your stuff to the school literary magazine. For adults (or anyone), it gives you a way to express yourself, and even if no one reads it, a way to help you organize your thoughts. Weblogs rock.