Constrictor is an almost-direct port of Blosxom to Python. I really like the design of Blosxom, but I find Perl fairly annoying to work with and would much prefer to use Python.
If you're already familiar with Blosxom, you should check out the page of major differences between the two.
A lot of documentation is yet to be written, but I've set up a page of information about items in the state dictionary which should be useful for plugin writers or porters, and you can view some sample plugins. Of course, the best place to understand how it works is to get the code.
Like Blosxom, Constrictor is available under the MIT license.