PHP can highlight itself. It's built in to the language. So any board written in PHP usually supports highlighting PHP.
One thing I was wondering was how come the php script-colour-er is enabled. Not so much 'why is it enabled', I know it's in a good few programming forums, but why is it so common around the place? Is it just ... there or something?
Now that's an idea!
>> Perhaps it could be colour coded and the viewer could choose the style, in their User Profile or something?
Yeah, that's what I suggested. Could be defaulted to nothing and you change it, or something.