For anyone who was overly excited, like me, the OS X binary is just a client for external Docker hosts.
I heard rumours of a osx distro that ships with qemu for out of the box experience, but could use vagrant if you have it.
I wish I’d read your comment before getting excited. :)
For anyone just wanting to play around with it, I posted my quickstart mac recipe on github: https://github.com/robey/docker-layercake