In a previous blogpost, the Docker team outlined how LXC will become a (albeit native) plugin, just like AUFS. Running Docker on BSD (using Jails as the container provider) is certainly a goal. If you're on OS X, you could use chroot instead of full namespacing capabilities.
To be fair, this is not available today. But I don't think it's fair to say that Docker will not be useful anytime soon on those environments.