I'd definitely like to have that 500 pages book in my library as reference, and give the shorter popular book as gift to friends (or my future kids?).

Only a small subset of the small group (relatively) of people who have read these blog posts as they were published will use them as reference later. Almost nobody (relatively) will be rediscovering them in a few years. That's simply the nature of blogging. Who's reading 3 years old BoingBoing posts right now?

I'm currently reading "Godel, Escher, Bach", and from what I've read here, I think that Eliezer's book could become something like that. Maybe not a Pulitzer (but who knows?), but certainly something special that changes the way people think.