I think most people don't use mod_python directly, but instead use it as a means of running their web framework. So, for example, django comes with support for mod_python (http://www.djangoproject.com/documentation/modpython/).

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).