If you are going to operate a cloud at scale then you most certainly need to use some ways to automate the configuration and other tasks like provisioning when you spin up cloud infrastructure. One of my favorite open source projects for doing this is Puppet sponsored by Puppetlabs.
Puppet is a client-server application that allows you define roles and configurations for infrastructure in puppet manifests then deploy those manifests across numerous servers simultaneously. In addition Puppet has another project, the Marionette Collective (MCollective), which allows you to automate common tasks and works in conjunction with puppet.
One of the best ways to get up to speed on using puppet is to attend a Puppet Camp. The next one will be hosted inAtlanta on February 3rd.
“Puppet Camp is a community oriented gathering of Puppet users and developers. You’ll have the opportunity to network with a diverse group of Puppet users, benefit from insightful lectures delivered by prominent community members, and be able to share experiences and discuss potential implementations of Puppet during our attendee generated breakout sessions.”
If you can’t attend this session there are many other Puppet Camps being held worldwide listed on the PuppetLabs website.

[...] Learning Automatic Configuration Management with Puppet [...]