Puppet: A network tool for managing many disparate systems
Puppet 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.
Puppet's simple declarative specification language provides powerful classing abilities for drawing out the similarities between hosts while allowing them to be as specific as necessary, and it handles dependency and prerequisite relationships between objects clearly and explicitly. Puppet is written entirely in Ruby.
For more information visit the puppet hompage at http://www.reductivelabs.com/projects/puppet/index.html.