Deis is built on a lightweight Linux distribution that is built to run containers, called CoreOS, and on Docker to take advantage of the distributed services, such as etcd, available there.
"Deis is a lightweight application platform that deploys and scales Twelve-Factor apps as Docker containers across a cluster of CoreOS machines."
I found Deis to be a very promising project and would like to work with it more. I have barely touched it but what I have seen so far looks good.
Deis can deploy any language or framework running on Linux using Docker, and it also includes Heroku buildpacks for Ruby, Python, Node.js, Java, Clojure, Scala, Play, PHP, ...