On the Zend Developer Zone there's a recent tutorial from Chris Renner focusing on the use of the Zend_Cache component of the Zend Framework to increase the performance of your site by caching chunks of data to easy retrieval.
The applications I develop and manage are very heavy with database transactions. Hitting the db every time you need an object is a serious performance bottleneck, and on a shared environment can be troubling to other applications living in the same environment. I'm going to describe my experiences with Zend_Cache here, but I am not going to bore you with lots of code detail and specifics.
He talks about the frontends you can use to cache the data to different types of formats, includes a code example for caching objects with the component and how to clear out the cache when you need to refresh the content.