I'm currently in the process of cleaning up and packaging Oort - a Python-based thingy used for making web apps driven by RDF graphs (there will be more where that comes from, rest assured).
Following is my little list of good starters when doing Python package development.
Most obvious: take a good look at setuptools (especially the concepts and usage of eggs, easy_install and pypi).
For testing, Nose is my one-stop-shop for now. Avoids the articificality of the xUnit-API; uses automatic discovery (with filtering); finds doctests if desired; uses coverage.py if available.
It's probably always wise to follow the practises of the most modern and well-renowned packages. I think Paste is a good example of this.