It is a cloud agnostic service orchestration tool developed by Canonical. So of course you're using ubuntu images here but it allows deployment and service integration just like we saw on the video. It does not uses docker but Linux containers which is a level lower on the stack.
The magic happens in reusable components called charms (a bit like cookbooks in chef but with different purposes) which defines the installation logic and hooks to run when you want to integrate another service.
I really liked the concept behind juju and was convinced when I saw how I could deploy and configure a MongoDB cluster with replicasets, shards, config servers and mongos with just a few commands.
Anyone else heard about it? It looks like they're not communicating too much about it. And with Docker becoming the de facto standard now, I don't know how it's going to evolve in the near future.