Heroku, with its 12-factor application model, has changed the way we think about building, deploying, and hosting web applications.  Deis encapsulates the Heroku PaaS model in an open-source framework that deploys onto Docker containers hosted anywhere.  Deis is still evolving, but for applications that fit the 12-factor model it has the potential to greatly simplify deployment and hosting in the environment of your choice.  Deis is yet another example of the rich ecosystem of platforms and tools emerging around Docker.