HOW A BLOGOSPHERE STORY GROWS: An interesting piece, though I wish there were more detail. This part certainly squares with my observations:

Rarely can an individual blogger get a story going. It is far more usual that several bloggers blog about an occurrence, an event or a comment elsewhere and then after that bloggers in groups get going. Even a so called influential blogger blogging about a story can rarely get others going. It is only when there are several bloggers writing opinions does a story really get going.

Yep. Which is probably a good thing. (Via Doc Searls).