Even though I'm quite happy with WordPress, I'm mainly coding in Python nowadays, and wanted to eat my own dog food, ie improve my Python knowledge by studying the source code and contributing with plugins (if the engine allows it).
After searching, I've already encountered Byteflow and PyBlosxom.
Byteflow works using Django, which for me a minus (I would prefer a small, simple codebase, not dependent on a big framework. This excludes Plone also, unfortunately).
What other options are there?