Using Optparse, Subprocess, and Doctest to Make Agile Unix Utilities
Use subprocess.call if you don't care about stdout. Otherwise, use subprocess.popen.
Noah really emphasized the importance of making full use of the Python standard library. There's a lot of good stuff in there!
When giving a talk, remember to use large fonts and small code snippets.
Here's a neat idea: consider adding an --upgrade flag to your program that uses setuptools to do a software update.