It me an hour to figure out that to not get 404 errors, you have to make the primary function called index. Now I'm trying to pass a variable in the URL and retrieve it. This is simple in PHP, and in Python I would think it would just be a dictionary.
The official documentation from mod_python is virtually useless. Even a list of classes and functions and how they work would be great.
mod_wsgi (http://code.google.com/p/modwsgi/) is rapidly becoming popular, it's an implementation of the python wsgi spec which has a plethora of toolkits and libraries available.
If you want to go low level I'd recommend mod_wsgi + a library like webob. Otherwise I recommend django on top of mod_python (or mod_wsgi).