Seth Israel asked Robert Scoble to do a book about blogs. Robert accepted on the condition that the book be written as a blog itself and where the rights would be sold on eBay. So, it's going to happen.
Indeed this will be a very interesting exercise and might signal a new "thing" in the world of publishing. The readers of this blog will certainly contribute to the accuracy and throughness of the work. I hope they finish quickly because the idea-flow in the blogosphere might make the first half of the book irrelevent if they take too much time with it.
Jeremy Enright has started his book too and mentioned a co-release with Scoble & Israel which I think is a great idea.
This blog to book idea could be hugely impact in LOTS of disciplines if it catches on. Many, many technical disciplines (biomedical science, IT, etc.) could all benefit from this format. However, I think that the publishers would be scared to death about not having an embargo on the HTML content of the blog. Moreover, the printed book would only represent a snapshot of the blog while the story of the blog would be written/revised in perpetuity.