In this new post to his blog Mike Purcell gives you the full instructions to getting a CentoOS 6 system up and running with Memcached and PHP.

Recently I started retro-fitting the MeLikeDrinks.com drink website to cache frequently used data to improve performance, as such I wrote a light, custom cache API which sits on top of PHP's Memcached API. [...] If you opt to use PHP Memcache, and because this article assumes you are using CentOS, you can simply have YUM install the entire stack for your via `yum install php-memcache`.

He describes some of the differences between the two memcache APIs available to PHP developers (memcache and memcached) and includes the instructions to get both versions installed. "Memecache" is as easy as installing the package, while "Memcached" takes a bit more work - installing dependencies, configuring and compiling a few things specific to your system.