The Perl web site at http://www.perl.org/ has documentation, tutorials, and links to several wonderful resources. O’Reilly has several very useful books about Perl. “Learning Perl” and “Programming Perl”. Get “Learning Perl” if you need to learn programming, and get “Programming Perl” if you already know programming but want to learn programming in Perl.
If you’re familiar with Perl but need some solutions, the “Perl Cookbook” is very useful. I have a review of it at http://www.hoboes.com/Mimsy/?ART=118. If you look down towards the bottom of that page you’ll also see one or two related Perl articles.
Finally, “The Perl Desktop Reference” is a great desktop--and pocket--reference to the Perl syntax and language.