See the cover of this book? That black circle that contains the words “Ubuntu 8.04 on DVD” and some smaller writing that you can’t really read in that image? I saw it in the bookstore today.
It says “Free upgrade to 8.10.”
Earth to publisher: Ubuntu is free software. That means that they’re all free upgrades, and anyone who knows enough to want the book will pretty certainly know that already. Sheesh!
(Disclaimer: I only looked at the cover, I didn’t even open the book, so I can’t recommend it.)