I just finished doing a simple web interface for managing our automated documentation builds.
First impression of Catalyst: Damn. Nice.
Annoyances: that the Static plugin uses File::MimeInfo which after a lot of code reading tunrs out to use some unix specific sheit that doesn't work that well on Windows. So I did the mime mapping manually instead (should probably be pluginized).
Ajax things on the other hand turned out to be ridiculously simple! The shoulders of giants and all that.