If anyone wants to learn constraint programming, as I needed to do a few months ago, the two best books I found are this one, which is a general introduction:

http://www.amazon.com/Constraint-Processing-Kaufmann-Artific...

... and this one, which is a survey of the literature:

http://www.amazon.com/Constraint-Programming-Foundations-Art...

None of the other books I looked at was even close to as useful as these. Maybe this will save somebody some trouble.