I don't know that I'm sold on the need. Syntax highlighting is cool, but as often as not I find that many editors prove the old adage that "Only perl can parse Perl" (ie, highlighting is occasionally goofed up by odd syntaxes).
in reply to Feature Request: Adding Colors to Source Code
Combine that with the fact that code tags are used for a lot more than just Perl code, and you end up with a difficult to implement problem.
As far as readability, I don't really find syntax highlighting all that big of a deal anyway. If you write clean code, with proper indenting, sufficient whitespace, and clear idioms, you end up with something that is going to be legible with or without highlighting. If you want to write illegible code, we have a section for that too, and I have a feeling syntax highlighting won't help there either.