While Jarkko Hietaniemi (whose quote is currently at the bottom of this page while I'm writing) worked in Nokia he worked on porting Perl to Symbian OS. This is definitely not an easy task, having seen a portion of the Symbian OS C/C++ API and figuring I'd delay my aspirations of writing programs for it to make sure my N95 would alert me if it was stolen (already mapped out the program for it, trust me).
Apparently, Jarkko has also made a lot of progress in that front and there is working Perl on Symbian OS. I've read that perl 5.9 is being used (since it's easier to change and patch because it's not a stable release) but I've also noticed that there's a Symbian README file with 5.10.
They are still working on it, so it seems, since 0.4.2 came out on March 2007.
However, Python seem to have evolved rather nicely on Symbian and Nokia even took it under its wing (and also wrote a book on it). They already have full access to the API, including UI (through the appuifw module), so I'm gonna fiddle with that. However, once perl will reach a level of full compatibility (or most), I'll probably switch back.
Expect complaints on Python in the next few months/days/hours/minutes/3..2..1..