Actually, the way I see it, if the book is interesting for me to read, then it'll probably be interesting for my friends to read as well. I don't love the tactic, but I don't think it's that bad (assuming I know the book is interesting, and not a completely speculative thing).
Understanding this attitude towards both blog posts and previously published content is very, very, very important for people publishing on the Internet, which should be substantially every business on HN. It came up in discussions with two clients and two prospects just in the last month alone: whatever you make, don't call it a blog post, or it will a) autocommoditize the perceived quality of the piece and b) cause it to start losing value immediately upon publication, which is the exact opposite of what you want.
