I updated to the newest Wordpress. The main reason for doing this was to be able to write source code, as I needed to post some code for a problem I have experienced in MOSS (well, who hasn’t?!) In this post (thanks Matt) I saw that in version 2.5.1, it should be quite easy. By using the new shortcode feature of Wordpress, it should be really easy. After installing, though, I just couldn’t get it working. After some searching I found out from this post (thanks to the unknown author!) that I needed to install the Google Syntax Highlighter for WordPress. After the install, I was able to write the sourcecode nicely syntax highlighted 
Here is an example.