I just picked up Learning Perl Objects, References & Modules and I'm enjoying it so far. For my level, this book is a perfect fit. I've fiddled around with these subjects before (perltoot, perlref, perlobj etc), but I like having a well laid out book in front of me with excersies I can follow. I think that once I learn a bit about these topics, the perldoc's will be a good reference. This book is a good beginner guide.
I'm hoping to go back and modulize some of my existing work, and I'm excited to try it. I am definately not going to go at it ad hoc as I am used to - planning ahead will be a requirement from now on I think.