Daily builds of docker master branch are available in the virt SIG repository as package 'docker-master': http://cbs.centos.org/koji/buildinfo?buildID=690 Should mostly work fine though use it AT YOUR OWN RISK.
If you'd prefer to use something stable, you could choose between the RHEL-recompiled 'docker' package available in centos-extras and the 'docker' package available in the virt SIG repository.
Feedback/comments/bugs/patches welcome.