Pinax is an open-source platform built on the Django Web Framework. By integrating numerous reusable Django apps to take care of the things that many sites have in common, it lets you focus on what makes your site different.
PyFacebook is currently best-tested with Django, and if you are just starting out with Python web development, the author highly recommends this combination :-). If you'd rather use another framework, there are also Pylons and other WSGI helpers in PyFacebook as well.