Is site-packages appropriate for applications or just libraries?
We do it like this.
Most stuff we download is in site-packages.  They come from pypi or Source Forge or some other external source; they are easy to rebuild; they're highly reused; they don't change much.
Must stuff we write is in other locations (usually under /opt, or c:\opt) AND is included in the PYTHONPATH.
There's no great reason for keeping our stuff out of site-packages.  However, our feeble excuse is that our stuff changes a lot.  Pretty much constantly.  To reinstall in site-packages every time we think we have something better is a bit of a pain.
Since we're testing out of our working directories or SVN checkout directories, our test environments make heavy use of PYTHONPATH.  
The development use of PYTHONPATH bled over into production.  We use a setup.py for production installs, but install to an alternate home under /opt and set the PYTHONPATH to include /opt/ourapp-1.1.
I'm in a bit of a discussion with some other developers on an open source project. I'm new to python but it seems to me that site-packages is meant for libraries and not end user applications. Is that true or is site-packages an appropriate place to install an application meant to be run by an end user?