This Wednesday the 20th, I'm speaking at the Boston Python Meetup: Getting Started Testing your Python. Please do come if you're in town. My goal will be to provide a totally from-scratch introduction to how to test Python code, in two hours, with time for questions.
I think I may have too much to say, though. The presentation itself is available for review. It could use another (hundred) pair of eyes. If you have any suggestions about what I should leave out, what I need to add in, what I've done completely wrong, and so on, let me know, either in a comment here, or in an email.