New from ZendCasts.com there's a webcast about testing models in your Zend Framework applications.

A walkthrough on how to build up a simple model layer using a test-driven development approach.

You'll need a project already set up to follow along (he doesn't walk you through the creation of one or the setup of PHPUnit) but the process is pretty simple. He shows how to create some unit tests with the TDD method to help create better code through anticipated feature testing.