Perl Quality Assurance Projects:Directory and coordination point for CPAN testers, the Phalanx project, and articles and general information about Perl testing.
An Introduction to Testing: Article on perl.com by chromatic, which explains why writing tests is good and how to go about it.
Automated Testing With Perl: Slides for an introduction to Perl tests, with an overview of the CPAN testing modules.
LectroTest: Automatic, specification-based testing tool for Perl, that by running repeated random trials against the code being tested. FAQs, lists, forum, and talks.
PITA - The Perl Image Testing Architecture: A draft that attempts to comprehensively solve the problem of mass testing Perl packages against a wide variety of different environments.
Testing Modules Available on CPAN: An fairly comprehensive survey of the many testing modules available in the Test:: namespace.