I think that Perl documentation, being integrated with the code is a problem. Perl does have better documentation a lot of other languages. However, in order to update/change the documentation, you have to get the author to update their distribution.
The other limitation of this is that is hard to include examples for code that is is outside the scope of the immediate module, example: Code on how to integrate Module Foo and Module Bar.
I would like to see a Perl Wikipedia be set up. We need to be able to provide more documentation than is available in a CPAN module or the Perl faqs.