There's a built-in "Code highlight" plugin
Open Global settings > Plugins > Install new

I've been using AstonishMe's "Code highlight" since I started using b2e. It only supports PHP, XML and CSS. If you want support for other languages you have to start messing with the plugin class files and css. No thanks!

There have been plugin wrappers for syntaxhighligher, which is definitely the way to go. Let another project handle the strain of keeping a code highlighter up to date.

I've been trying to convert the code_highlight_plugin to use syntaxhighligher but I got so little help when I asked about renderer plugins that I've been struggling:
http://forums.b2evolution.net/viewtopic.php?t=24504

I know it was you that answered that as well! So I thought I'd ask here in case someone has written this wrapper for us already. I found a few but they all tend to be on other peoples' blogs and so it's difficult to see which is the latest.

I agree that current code highlighter is very limited, I don't like it either.
Can you post links to those blogs?