In this recent post to his blog Madarco shows how to create a simple Facebook application using the Zend Framework as the backend.

I've just finished a Facebook game, so here a quick tutorial on how to use Zend Framework to build a Facebook Application.

He talks about integration with the Facebook site (either in an iframe or using their custom FBML markup) and the code to create a simple controller/action combo to work with the first. There's a class you'll need from the Facebook developer site to get it up and working, but it's a super simple process with immediate results.