Shlomi Fish brought up an angle to the problem with slapping a boilerplate "same terms as Perl itself" at the bottom of your modules when you distribute them: Which version of Perl do you mean?
For me, I've used that line out of laziness, because I didn't care to think too much about specifics of the details. Now I'll be going back and specifying in my modules.
I've recently been updating the license info on my modules as I prepare any new releases. It was inspired by someone from the Fedora Core project wanting to include RPC::XML but the old license verbage wasn't compatible with them (that was solved by me sending a message giving them explicit permission to release under LGPL).
Now, I explicitly state that license/distribution is under both Artistic 2.0 and LGPL 2.1, and I provide links to both licenses in the POD of every module. Overkill, maybe, but effective.
Note that, contrary to Shlomi's article, (most of) Perl 5 is GPL version 1 licensed, not version 2. This in and of itself may be enough to prompt some to be more specific.
But I'd rather see a campaign to get modules to state some license (and a bug-reporting mechanism, to boot); far too many do not.