A while back I finished a pretty good book on python Python Scripting for Computational Science by Hans Petter Langtangen (link). It was a pretty good introduction to python. I really liked the slant towards the sciences and engineering. The problem sets were good.
Currently I am reading Building Skills in Python by Steven F. Lott (pdf). It is a thorough piece on the python language. It even has had an effect on my .Net programming style. I really appreciate the dictionary data structure!
The next book I am planing on reading is Building Skills in Object-Oriented Design by Steven F. Lott (pdf).