I am listing the places that I hold in awe as being the best places to be at if you want to improve your Perl skills.
ActiveState Vancouver, BC, CANADA Ever hear of Data::Dumper by Gurusamy Sarathy? How about Inline by Brian Ingerson? Well guess what. *Both* of these cats work at ActiveState. Talk about a nosebleed company. Oh. Forgive me. I almost forgot Gisle Aas, author of LWP and original author of HTML::TreeBuilder and developer of perl-lisp works there too.
Canon Research Centre (link down at moment) London, England They won a Perl wizards contest long ago. Andy Wardley , author of widely acclaimed Template Toolkit works here. Also, Neil Bowers works here. He developed cpan-upload, which puts things on CPAN via the command line via Net::FTP and LWP among other highly useful things.
Morgan Stanley Dean Witter Mainly New York City This place has a massive investment in Perl. They have weekly tech talks that often focus on Perl. Every time I put out my resume in New York, I had an interview with a different group there that was developing 90-100% of their code in Perl. They were going to buy Damian outright, but their offer was rejected by Yet Another Society for some reason.This interest in Perl, coupled with their stability, excellent pay structure and benefits package as well as huge fault-tolerant Perl infrastrcture built upon years of experience as a major Wall Street firm makes them a viable place to work. That being said, their corporate structure sometimes makes using CPAN an issue. And most groups won't be using DBI but rather use Sybase's sybperl instead.
Evolution New York City Well, M. Simon Cavaletto, developer of Data::DRef and Class::MakeMethods is here. They were one of the first people to develop in-line HTML templating via Evoscript.
Riskmetrics New York and abroad japhy is here. Other people have interviewed there and reported good experiences
Ticketmaster Pasadena, CA They are responsible for doubling the speed of Template Toolkit. They are a very major open source Perl shop, serving hundreds of thousands of hits via mod_perl during the week and probably 10 to 100 times that on the weekend. Even the recruiters there seem to be good programmers. They are also employing Stas Bekman to do basic research on mod_perl which will improve their applied development on their website.

And of course you have your one-man shops like ECOS, Codewerk, Stonehenge Consulting and Magnum Solutions