The release classifiers in this post should be included in the standard distutils documentation. For the moment, you can see the full list of classifiers here:
http://pypi.python.org/pypi?%3Aaction=list_classifiers
For the python language version the classifier is:
Programming Language :: Python :: x.y.z
With each version on it's own line. That way you can browse the repository by python version (see the bottom of the page):
http://pypi.python.org/pypi?:action=browse&c=214
There is also support for frameworks which you can see on that page as well. There it is done with:
Framework :: Django :: x.y.z
There is Zope, Plone, and a number of other frameworks already there.
In the example you gave the proper, and supported way of writing the metadata is:
Programming Language :: Python
Programming Language :: Python :: 2.4
Programming Language :: Python :: 2.5
Programming Language :: Python :: 2.6
Programming Language :: Python :: 2.7
Framework :: Django
Framework :: Django :: 0.96
Framework :: Django :: 1.0
Framework :: Django :: 1.1
Framework :: Django :: 1.2.1
Framework :: Django :: 1.3
Now it becomes a matter of education and illumination. This should be in the standard distutils documentation and arguably the home page of PyPI (or easily found there). And Django Packages will be supporting this functionality in the near future.