Hasin Hayder has a new post talking about the new memcached extension for PHP (memcached from PECL) and how it can be used to store sessions data.
Many of you already know that managing session is a critical task for web applications, specially when you want to avoid I/O hop and also a significant load over your database by writing a custom session handler. [...] This is why a central session manager is very important for your application to scale.
He walks you through the whole process - installation, setting up memcached instances and getting the extension installed and working with your PHP installation. By adding two lines to your php.ini file, the sessions can quickly and easily be stored in memcache instead of on the local server.