There is much buzz around PHP tools like Drupal and Joomla. They are ready-made solutions, but in fact there is also a lot of tweaking the templates and writing add-ons. It seems to work very well - the clients get something usable from the beginning - and later they can modify it to fit their purpose better. This is very agile. In contrast the reuse in Perl is mostly around libraries. This is much more flexible - you don't tweak a ready solution - you assemble it from the thousands of CPAN packages. But it is also less agile.
I wonder why it is like that. There are some technical differences that lead developers in one or the other direction - but there is also a cultural/psychological cause. Doing some self-analysis I must admit that I am not really enthusiastic about contributing to a Perl CMS (like for example Bricolage) - in my view all the already-build solutions use obsolete libraries. I'd rather contribute to building the perfect library - then code an extension to Bricloage. I have the feeling that I am not alone in that crazy perfectionism around Perl hackers. PHP clearly wins here with more pragmatic approach.