It works in a none-obtrusive through an input filter, that looks for all pre or code tags and modifies then as needed to enable the highlighting. That has the benefit of making it easy to replace or remove later, as the original node text is not modified.
The administrator can also control the styling and add support for additional programming languages through an configuration section.
Right now the code is just hosted on my github account. I did search through existing modules and did not find any existing ones that uses Prettify, but even if there are some, this was a good learning experience for me.
Code available at: https://github.com/egil/prettify-drupal
Any feedback is much appreciated.