This is coming from left field, but my favorite CMS is actually written in PHP. It's LucidCMS, which my web clients just love.

You might notice if you look carefully enough that I have a commit bit I've yet to use directly in the SVN for the plugins and that I help answer questions on the forums as I get a chance.

It takes very little time to install, it's easy to write plugins for it, it has a database independence layer, and it has a tag-based template system for page parts.

My business partner and I have been discussing whether I should port it to Perl as I have time so that I can customize it and write plugins for it even more easily. There's already a Python clone of it in development called PyLucid. If anyone is willing to help with a Perl port, I'd be happy to know.