Memcache module provides handy procedural and object oriented interface to memcached, highly effective caching daemon, which was especially designed to decrease database load in dynamic web applications.
The Memcache module also provides a session handler (memcache).
More information about memcached can be found at » http://www.memcached.org/.
For those wondering about Memcache and Memcached APIs, Please go through http://code.google.com/p/memcached/wiki/PHPClientComparison and http://serverfault.com/questions/63383/memcache-vs-memcached