I was at Gluecon 2013 a few weeks ago and caught a great session from Jeff Lindsay & Solomon Hykes about Docker. Docker is an open-source engine which automates the deployment of applications as highly portable, self-sufficient containers which are independent of hardware, language, framework, packaging system and hosting provider.
The coolest part of the talk was when Jeff gave a demo of a mini-Platform as a Service he created the previous night dubbed Dokku that was built on Docker and running on the Rackspace Cloud. Check it out in the video below. The demo starts at 21:00.