It's the same thing as BSD Jails, however there is one big difference with Docker. A container/jail can be shipped to another system running a completely different kernel. This means you can create an Ubuntu 10.04 container and run it on an Ubuntu 14.04 host or RHEL 7 host.
With BSD Jails, you can only ship your jails to the same system unless you spend enough time fiddling around so you can basically do the same thing. Luckily the Docker team is already adding BSD Jails support.