There's a few things going on with python packaging ... a few PEPs and
some implementation.

PEPs:

* http://www.python.org/dev/peps/pep-0376/ - basically, let's
  *actually* keep track of what's installed with an API ; this ain't
  *the wild west anymore, people (well, maybe with the Mission being a
  *notable exception)

* http://www.python.org/dev/peps/pep-0345/ - let's reconsider metadata
  and actually make use of it (there are PEP 314 and 241 but of course
  the setuptools author decided that some things he should just do
  whatever the hell he wanted)

* (PEP 386 for version comparison, but less interesting)

And...the implementation.  Its called distutils2 but will be called
packaging in python 3.whatever and there's more name confusion too but
I'll stop there

http://wiki.python.org/moin/Distutils2

I couldn't find a great reference but
http://pythonhosted.org/Distutils2/ is probably okay.  More
pragmatically, look at its own setup.cfg file:

http://hg.python.org/distutils2/file/65e23cccd0db/setup.cfg

http://www.aosabook.org/en/packaging.html