On Developer.com today there's a new article talking about memcache and how you can implement it in your application to provide a performance boost for applications in a distributed environment.
As distributed system is part of the Memcached definition, you can install Memcached on various servers to make a larger caching server. In this way, Memcached helps reduce database loads to a minimum, resulting in faster and more responsive Web applications
They take some time to explain what memcache is - a simple to use caching system that reduces the dependency on other data sources - and how to get it installed (via the package manager of your choice). They suggest times on when and when not to use it as well as some of the security implications you'll need to worry about when implementing it. There's also a bit of sample code to help you get started in your application. You'll need the memcached extension to make it all work, though.