In addition to the public search index and support for data volumes, this release also includes an open-source version of the registry. So anyone can host their containers privately without depending on the central registry.
I'm glad Docker is getting this level of attentions. I like that they have focused on making building and managing containers easy, and that this functionality stands alone. Compare this to, e.g. Red Hat's OpenShift, which implements a similar container system but bundles it as part of a larger PaaS platform.
I like the new description line of "Docker is an open-source engine which automates the deployment of applications as highly portable, self-sufficient containers" better than the old one: https://news.ycombinator.com/item?id=5609995. "Improved, as promised" seems to a major theme here. :)
I don't know the specifics but it uses standard (if new) Linux kernel tech: LXC [1], namespaces [2], cgroups [3] and AUFS [4] to create something similar to a BSD or Solaris jail.
Hipache: https://index.docker.io/u/samalba/hipache/
Heroku buildpacks on Docker: https://groups.google.com/forum/?fromgroups=#!topic/docker-c...
Ready-to-use OpenCV build with python bindings: https://index.docker.io/u/steeve/opencv/