On the ZendCasts site today there's a new video looking at the Zend_Cache component of the Zend Framework and how it can be used to speed up the response time for things like calls to a web service.
This is part 4 in a four part series on Google Docs and Google maps. While this example shows how to cache a Class to a file, you could easily modify the code to work with other caching backends such as a memory-based caching engine or something like Zend Optimizer or APC.
If you want to get caught up on the series, here's the links to part one, two and three.