I don't know anything about Docker being production ready, but both LXC (used by docker) and OpenVZ are production ready. OpenVZ is a mostly equivalent technology that has been around for a number of years, but IMHO hasn't gotten the management features and updates that docker is getting.
You can use OpenVZ right now for similar things, but it isn't as easy to create small single-use containers.
The nice thing OpenVZ has that docker doesn't currently support is mounting a Host directory (read-only or read-write) into the OpenVZ container so you can easily share lots of data to many containers with one copy. Right now, docker supports sharing volumes between containers, but not with the Host system.
For example, you can make very small OpenVZ containers by using common /usr, /lib, /lib64 directories and mounting them read-only in all of your containers. It's easy to bring up OpenVZ on a Centos6 machine and you can run Ubuntu containers in it if you like.
I have nothing against Docker and hope they keep adding features, but my current experience is with OpenVZ.
Great! Thanks for pointing that out. I had read through the tremendous number of comments around that feature a month ago, and didn't expect it to make it through committee already.
This is a good point. There are two definitions of "production ready":
1) Works for my application.
2) Won't get my head chopped off.
The second is what most developers working inside a hierarchy really want. I am always torn in trying to keep up with new things, because reliability is generally not the focus of new products.
I'm always afraid of 1.0 release stuff for actual production environments, despite who releases it