gldnsup, the primary way to do what you want is create native packages for your distribution of choice.
and most of the distributions i want tend to do this using make / shellscripts / perl
it's silly to depend on python for installation for these common tasks.
If you've ever used bash to do somehing, bash -x somescript 2>&1 |less will tell you everything you need to understand, what the shellscript does, and at which point you might want to alter it.
the less non common stuff is needed to complete installation tasks, the better. and depending to install on python is non common.
Doing unit tests in python or whatever else language is ok, because neither building, packaging and package installation depends on them. You might even use hascel, ruby, java or fortran 77 for that if you like to.
If you like to reimplement parts of the server functionality in python, i would advise you to have a look at the groupware server of some belgian guys, they did the calendaring using python. on the average box it gets unusable slow while being used by more than 5 users at the same time.
