As the Zend Developer Zone points out, there's a new article from Erwin Early (of the i5 community) that's a shot introduction to what the Zend Framework is and some of what it entails.

The customer interest in PHP has been high and I receive numerous questions at customer events on its usage of PHP on IBM i. Many people also ask about Zend Framework. What is Zend Framework? Can I use it on i5/OS? How can I integrate the advanced functionality that Zend Framework provides?

To answer some of these questions he gives an overview of the framework - some of the components that make it up, how to place it so that Zend Core can find it, some resources about the framework and an example os its use to make a PDF with Zend_Pdf.