I just published
a lengthy Instructable on how to build a book scanner using salvage materials and cheap cameras. I also have software to process the output into PDFs, though it is very much a work-in-progress.
Thought you guys might enjoy seeing it, maybe some of you will make one? I'll do my best to support anyone who makes the attempt.
The quality of the samples on that page DO NOT reflect the best this scanner can do -- I was in a hurry to get it done before the Instructables deadline.
I've been lurking around the site ever since I got a PRS-500 cheap with a Sony card, but I was so bummed with the resolution/software that I ended up selling it.
PS. If you have an account at Instructables, please vote for my project!