From Fedora Project Wiki
On EL5, the "system" python binary, /usr/bin/python is Python 2.4, and all add-on python packages are for the 2.4 syntax, and byte-compiled for 2.4.
EPEL5 provides a parallel-installable Python 2.6 stack. The core runtime is in the "python26" package, and there are a number of "python26-*" extension modules already in EPEL5.
EPEL5 Packaging Guidelines
Python26 Bugs in Bugzilla
Review Request: python26 - Parallel-installable Python 2.6 for EPEL5