[CentOS] managing a rack full of centos servers

to date, I've done all my administration on a manual 1 at a time basis, as each system has been pretty much unique.

its looking like I might need to setup a deployment of a dozen or 2 basically identical machines, all running pretty much the same sorts of stuff. I have zero experience with the sorts of management tools folks use to automate this type of configuration, both initial setup, and ongoing management (system updates, user application updates, configuration changes, etc).

anyone care to suggest any such tools, maybe some real-world pros and cons? of course, being centos, I prefer FOSS tools. for various reasons, this environment likely will NOT be virtualized (although I may emulate a test setup with vmware).