Choosing a camera is an important step in your project, because it may affect what software you will be able to use during the acquisition stage.

For many users an important consideration is whether a camera is compatible with CHDK. You can check whether a CHDK build is available for your camera at the CHDK wiki: What camera models are supported by the CHDK program? Note that CHDK is targeted primarily at Canon cameras.

What also needs to be considered is the resolution of the camera.
Higher resolution will enable you to "scan" larger books.

Resources

This is a tentative list, built up by scanning through the forum. (For the time being, no guarantees of recency are implied, it's just intended to help you thread your way through the forum posts.)

The New "Standard Scanner" thread on the forum (by Dan) suggests the '''Canon Powershot SX200''', '''A1000''', or '''A590 IS'''.

Another useful thread:

Minimum Camera for Book Scanning

A discussion of Camera Resolution, and how MegaPixels are related to scan DPI.