I recently came across this article Build Web appplications with Maypole (A Perl framework for quick and easy database-backed applications) by Simon Cozens on the IBM DeveloperWorks site.
It explains a perl framework based on the popluar MVC pattern (model-view-controller) that creates a logical three tier architecture separating presentation, business logic and data persistence layers.
I am very interested in design patterns and it is good see they are having an impact on light-weight scripting environments such as Perl as well as on more heavy-weight development environments.