Having written a Ruby book I would definitely agree, even though my book was very modest in size it took an order of magnitude more work than I had expected. Coming up with code examples, editing, creating a book cover, not to mention how grueling it can be to write especially after a long day of coding.

All that and not even a single link to it? Where's the shameless self-promotion slash example?

Here is a link to the book. Yeah, I'm pretty shameless but haven't done much promotion yet :-)

http://www.amazon.com/The-Rapid-Rubyist-ebook/dp/B00DPQ5P24

Sure. 70 hours for the first draft and probably another 70 for the editing and revisions. I had the first draft done on July 1st, then spent two weeks editing before starting the preorders. I was developing the companion rails application at the same time so it's hard to get real numbers.