I originally wrote about the problem of saying your code is “licensed under the same terms as Perl itself” (which is prevalent for CPAN modules and other Perl code) on my Perl blog. It was also covered on Perlbuzz and covered there again. I’m only going to summarise these arguments here, and conclude by saying that using the Artistic Licence Version 2.0 or later, or a GPL-compatible permissive licence such as the MIT/X11 Licence would be preferable.
Essentially, the licence of perl (the Perl implementation) has changed several times since its inception - from a non-free licence, to the GPL, to a dual GPL and Artistic licensing. Furthermore, the Artistic license is not considered free and GPL compatible by the Free Software Foundation, so it’s not a wise choice, and the GPL has its share of problems too (see below) so it’s not a wise choice either.