It's probably also worth mentioning dokku, which is a simplified private PaaS built on top of Docker. It adds Heroku buildpacks (Ruby, NodeJS and Java right now) into the mix, and a git push-to-deploy model.<p>Because dokku has a concise and readable codebase, browsing the source is a good way to see one practical application of Docker, too.<p>I've set it up as a sandbox environment for developers at my company, and for our purposes it's a much better fit than some of the more heavyweight private PaaS products. I'm really enjoying working with it!
I played with Docker a bit yesterday. Containers really are awesome! VMs look almost stupid in comparison. I'll be using it as much as I can. Being written in Golang doesn't hurt either... Golang seems like a very good choice for this.