Seems like a very logical move. First we get stable CoreOS updates, now we have private Docker index built-in.
We need something like this for Chef cookbooks. Managed private and public API endpoints for organizations to host cookbooks that don't belong on the main community site,
Congrats to both teams. There's a lot of work to make clusters as easy to manage as single machines. These are definitely the right people to make it happen.
Definitely an interesting move, since Docker recently released their own private repositories with their 1.0