(I don't use either python or PostgreSQL, but perhaps this will point you in the right direction)
install mod_python with
yum install mod_python (if you want it embedded in Apache). You will need to configure Apache, see HowtoForge: embedding python
install python with
yum install python26 (if you want to go the CGI route, or run standalone scripts)
install PostgreSQL with
yum install postgresql-server (will automatically install the client)
I believe Django is a framework - in which case it is not required. The users who want to use it will provide it as part of their code.
Hope this helps.
Edit: As per the comment below, it does appear that mod_wsgi is preferred over mod_python.
It can be installed via
yum install mod_wsgi
If you need to compile mod_wsgi, there are instructions here. You can also find RPMs compiled against python 3.1.
If python is already on your system, run
python --version to determine the version. If it is an older version, and you compile from source, this article provides a procedure at the start (for not overwriting the existing python).
If you don't have an up-to-date python in your yum repository, you can try EPEL, which has python26-2.6.5-6