emacs has cperl-mode, courtesy the unstoppable Ilya
Zakharevich (you can get it from
his
CPAN directory). It can handle syntax colouring, too.
M-x font-lock-mode is what does it, I believe. I've never
paid too much attention to the intimate nasties of Emacs'
colouring and font fiddles.
There's PerlBuilder, but my experience with it was not
encouraging. David Grove, known primarily for paranoid
anti-Microsoft anti-Activestate rants, has released a
commercial Perl IDE called
Code Magic. I haven't seen it, so can't say how good
it is.