There’s an impressively in-depth presentation from [OSCON 2008](http://en.oreilly.com/oscon2008/public/schedule/proceedings) about [Practical Test Driven Development in Perl](http://assets.en.oreilly.com/1/event/12/Practical%20Test-driven%20Development%20Presentation.pdf). It covers Test::More, Test::Class, Test::Differences, Test::Deep and Test::MockObject.
I also found the following to be interesting: [Even Faster Web Sites](http://assets.en.oreilly.com/1/event/12/Even%20Faster%20Web%20Sites%20Presentation%202.ppt) and [Pro PostgreSQL](http://assets.en.oreilly.com/1/event/12/Pro%20PostgreSQL%20Presentation.odp). Reading these helps me to know a little bit about what I don’t know.