I use Perl almost exclusively. CPAN is my one word argument. Aside from that, though, Perl can become whatever you make it. Want Ruby-like method calls on literals? Use autobox. Want list comprehensions? Map/grep. Want to rip apart language built-ins at runtime, tie data sources to filehandles, or just use it for one-liner awk replacement? Done.<p>Python and Ruby are sexy but they both feel like subsets of Perl to me.
An honest question: are there any reasons to learn Perl these days (as opposed to Ruby/Python/name your favorite scripting language)? Some people need to maintain existing Perl codebases for sure, but they should know Perl already?