An excellent thread. My own two cents' worth to add (measly as they are).

Performance and development time: There are multiple applications running on various servers where I work written in Java, and on most of those machines, very little else. Both the load and number of processes from Java on those machines is generally quite high. In one of those applications, the Java system was replaced by an in-house built Perl system, which, on the machines it interacts with or runs on, is less taxing and faster. For the in-house application of which I spoke, development time was under 40 days, while it is my understanding that the Java system it replaced, a company's existing product, took over a year to be set up to work as required. (Apples and oranges, perhaps, but many times it isn't the flavor of the juice that a company cares about, just that it is something wet that slakes their thirst.)

Resources: CPAN is a great resource, no argument. There seems to be one other resource that I have not seen mentioned in the responses thus far-the perl community itself. From what little I have seen of programmers of other languages, perl seems to be the only one with such a strong, friendly group that doesn't mind helping a newbie programmer to the language that the word "community" can truly be used. (This site being a prime example of that.)

Fun: Okay, I admit, I enjoy playing with perl. Perl is a very useful tool, but I have never seen as much poetry or art expressed in a language before. That people can actually enjoy using a language, in addition to getting whatever the job is done with it, is a big plus.

The other reasons I could mention seem pretty much to have been covered already. For me, perl is a very fun, very useful tool. One of my co-workers is fond of joking, "That perl, she's a good ol' girl," and she truly is, whose acquaintance I am glad to have made.

Update: Corrected link to CPAN, with many thanks to Aristotle for catching it and advising me of the problem.