Why not run all your tests all the time? A study of continuous integration systems
Titus has some notable quotes "just use Hudson" but overall a good introduction of CI and a breakdown of some of the challenges behind continuous integration. He also does a good job going over getting started with Hudson, setting up a basic Python project that incorporates JUnit XML reporting and slaves.
"Yeah, we used Buildbot until recently, then I switched us to Hudson and my life got a lot better"
If you're using Python with Hudson, I highly recommend watching the talk (embedded below).