New on PHPBuilder.com there's a tutorial from Jason Gilmore looking at caching data with Zend_Cache, a component of the popular Zend Framework. He focuses on how it can boost the speed and overall performance of your application (even if you don't use the Zend Framework!)
Zend_Cache can be configured to cache several types of output, including the results of function calls, the results of object and static method calls, entire pages, and configuration data. You determine what data is cached using Zend_Cache's frontend. This data can be cached in several ways, including using system memory (RAM), using memcached, within text files, or within a SQLite database. You determine exactly how your data is cached using Zend_Cache's backend.
His examples use the Zend_Cache component on its own, so you don't have to wade through other Zend Framework-ish code to pick out just the parts you need. He implements file-based caching and shows how to set up both the frontend and backend options to make it all cooperate.