Christopher Webber gave a great talk about Blenders python API at this years US Python Conference. He shows some great examples of how python has been used in blender, and gives a really informative introduction to using the bpy python API.
Chris also provided links for the slides and an ogg version of the talk:
- OGG version here: http://dustycloud.org/misc/pycon_2011_blender_talk.ogv
- Slides PDF here: http://dustycloud.org/misc/pycon_2011_blender_talk.pdf
- Slides source files here: http://dustycloud.org/misc/pycon_2011_blender_talk_slides.tar.gz