"The most-read webloggers aren't necessarily the ones with the most original ideas, say researchers at Hewlett-Packard Labs. Using newly developed techniques for graphing the flow of information between blogs, the researchers have discovered that authors of popular blog sites regularly borrow topics from lesser-known bloggers -- and they often do so without attribution."
Wired News on infections and epidemics in the blogworld and this study. Do read the FAQs, especially if you want to know why bloggers kill kittens.