I was delighted to hear that Francisco Souza at globo.com had hacked up juju to work on CentOS!
Right now for juju we have clients for RPM-based distributions like Fedora, OpenSUSE, and CentOS (thanks to Brandon Holtsclaw). However this is just the client piece, in order to spawn the magical instances on the cloud you need other things.
Francisco has outlined how they did it in this blog post, quite clever, I had no clue people were even working on this. Nice job fellas!