This is exactly how I see these new ebooks, not so much as actual competitors to the oreilly kind of books (because they are more concise), but as longer form thinking than blogs. There's a lot of enthusiasm on self-publishing books, and maybe it will be short-lived, but I hope that in the long term we'll have more and more experts in our community who will share their knowledge on niche topics in the long, self-contained and polished form that books are!