Blog was broken because of a server upgrade. It was broken because the code I'm using (pyblosxom 1.4) was testing for the presence of a feature and behaving differently.
The feature is the standard library's wsgiref. If the wsgiref module is present, it tries to use it instead of just calling the CGI script directly. Unfortunately the wsgiref module uses some settings for PYTHONPATH that I didn't bother to try to figure out, so the script broke.