I have written large systems in the past using Perl, most of which could as well have been written in Python but would probably have required twice the number of lines of code. Where I use Perl now is for quick mutable tools and that is where Perl really shines.
Right at the moment I'm using a Perl script to validate digital filtering algorithms and configurations. I can paste a set of FIR filter coefficients into the __DATA__ section of a script and plot results with Tk using just a few lines of code. Tomorrow I may be using it to parse a log from a USB analyser or data from a logic analyser. In each case it will be a modest number lines of code written quickly and discarded just as fast. For that sort of task Perl feels much more productive than any other language I've used due largely to things like map, grep and Perl's simple but powerful data types.
If community is important then Perl leads the pack by a vast distance largely due to PerlMonks. I haven't seen anything like PerlMonks that is anywhere near as good for any other language, at least until StackOverflow came along.