On PHPBuilder.com today there's a new tutorial that walks you through the process of creating a simple MVC framework in PHP based on Smarty, PostgreSQL and the PEAR XML_Serializer package.
PHP now enables you to build robust, manageable, and beautiful enterprise web applications. The best way to do that is to divide the application into three components: model, view, and controller. In other words, you need to separate the presentation, the database, and the business logic from each other. The most common approach for achieving this design goal is to adhere to a strict Model-View-Controller (MVC) framework.
He uses the example of creating an application (a feed reader) to show how the parts of the MVC will fit together as a whole. You won't find any code examples in the article, just an explanation of how everything works together. You can, however, dowload the source and follow along.