Puppet is an application that "lets you centrally manage every important aspect of your system using a cross-platform specification language that manages all the separate elements normally aggregated in different files, like users, cron jobs, and hosts, along with obviously discrete elements like packages, services, and files."
Now there is no sane system administrator who wouldn't want to use all the tools available to make things easier for him/her to manage a cluster of servers, right? :)
So, if you are not insane, here's a quick run-down on how to install and configure Puppet on Ubuntu Linux.
Hurry, test it and give us feedback please.