First and foremost, I'd point out that Perl is available for nearly /any/ platform that they'll need. On Windows, ActivePerl comes with the Tk module already installed, so it is a great way to create quick little GUI apps that will work on Windows and *nix.

Another benefit is that one may switch between Windows and *nix while working on the "one perl script to rule them all" - this has its advantages when working with others on a project.

For different programmer's you'll need to highlight different things. Java programmers may want to see the "write once run anywhere" aspect of Perl.

You may also want to point out that in reality, 99% of the things that programs do don't require speed, and that difference in effort between writing a little tool in Perl vs Java/etc is huge.