It would make package maintenance easier, as well as integration with
other build systems e.g. autotools (necessary for projects where not
everything is Python), if the distutils supported an uninstallation
command, e.g.

python setup.py uninstall

This would presumably require monitoring of which files were installed
where, and it's of course possible to do undesirable things, but exactly
the same counter-arguments exist for autotools, and there the uninstall
target is an important and useful feature for developers, once you know
how to behave in a way to make it safe.

This would require a detailed description on how such a feature would work.

python setup.py uninstall 
should do all the same processing as 'install' but whenever it gets to
the point of copying a file to a system destination, it should instead
unlink the destination.

besides the obvious use, here is another one:
   when upgrading a package, and the new version no longer includes
certain files, just installing the new version will leave leftovers
of the previous version installed.  using uninstall beforehand will
clean out the cruft.

philobyte, this means you have to keep the source somewhere to be able
to run setup.py uninstall. This is not handy imho.

What about a uninstall registery in Python that keeps track of the files
installed for each package ? this would let us have an uninstall command
that could run on its own.

"uninstall packagename"

If an uninstall registry is feasible, the it could be neat. The
suggested behaviour of unlinking known files based on the source
directory is not all that inconvenient: it's by no means perfect, but it
has its uses and is familiar to many, since it is how GNU autotools behaves.

I will continue to discuss this in distutils-SIG:

Marc-André Lemburg proposed me to introduce the uninstall command from
mxSetup.py (from mxBase, http://www.egenix.com/products/python/mxBase/)

So I need to ask for opinions first

We're working on this as part of the distutils2 effort.  Current distutils (version 1) will not support uninstall.

Targetting 3.3

Status update: Josip implemented PEP 376 to provide the installation database and Alexis is working on distutils2.install_tools to provide an uninstall function. User-level tools like pip can reuse this code to provide an uninstall functionality.

distutils2/packaging now provides a remove function and a pysetup remove command.