Interesting. Just went to Amazon (not that I can afford anything these days) and got presented with a "plog", a list of blogs by authors I'd bought books by. Currently only Mark Guzdial (author of Squeak books) features on my personal list. But he had some interesting news from SIG on computers in computer science education.
Still, this could be very interesting. Amazon are practically forcing authors and readers into conversation with each other this way. People who shop at Amazon but never got into blog culture, are suddenly going to realize that their favourite authors are accessible.