I created a filter quite sometime ago that extends the codefilter module with syntax highlighting. I would like to make it available to the drupal community.
The syntax highlighting engine used is GeSHi (http://qbnz.com/highlighter/), which is written php so it is quaranteed to work where drupal works. I also added a config page that lets admin's enable or disable highlighting and set the default language. You can also change the behaviour on a per-item basis by passing arguments to in the code tag.
The have the code hightlighted in a language other than the default do this:
If you want to turn it off temporarily do this:
I would love to have this in the drupal repository but I amnot sure how to go about it yet, I will look into that in due time. In the meanwhile if you want to try it out I setup a project page for it at http://www.filbar.org/project/geshifilter.
Comments and suggestions welcome.