A couple of things that people who like this might also be interested in:

Coursera.org is currently running a course called "Audio Signal Processing for Music Applications" which I believe uses python. It's in its second week, so you have time to catch up. https://www.coursera.org/course/audio

http://aubio.org/ is a library that does note onset detection, pitch detection, beat / tempo tracking and various other things. It has python bindings.