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
This is only a draft at this stage.
--Dmalcolm 20:48, 2 March 2011 (UTC): some python packages are provided as part of the RHEL5 product. Others are add-ons provided as part of EPEL5.
If you want a python26 version of a package that's already in RHEL5, I suggest creating a separate src.rpm, and filing a review request for it.
If you want a python26 version of a package that's in EPEL5, I suggest opening an RFE bug against the existing src.rpm, and attaching a patch to it, adding a new python26-foo subpackage to the build.
TODO: byte-compiling
Python26 Bugs in Bugzilla
Review Request: python26 - Parallel-installable Python 2.6 for EPEL5
Dependency tree of all python26 bugs in EPEL5