I love reading BlenderNation. They always have the best news. Today there was a post about a free ebook on programming add-ons for Blender 2.5
Witold Jaworski has written a comprehensive 135 page ebook that explains how to program an Add-on for Blender.
I just downloaded it myself and plan on reading it as soon as I have a few minutes. Not that I have any delusions about becoming a master python programmer, but I do keep hoping that if I read enough about python, eventually it will take and I can join the python writing ranks. 😛