I would say that focusing on libcontainer vs. lxc vs. libvirt/libvirt-lxc, lmctfy or any of the container providers is important in how to work with the kernel

I would say that focusing on libcontainer vs. lxc vs. libvirt/libvirt-lxc, lmctfy or any of the container providers is important in how to work with the kernel and expose an API, but in general each have their own relative merits that suit different audiences. We would prefer and encourage for competition to exist at this level, but also to support all of the options with Docker as execution drivers. This is a small example of our approach in general - Instead of locking existing technology out, Docker is designed to integrate seamlessly the choices you're living with today. If we don't do that well, it's a bug. Let's fix it.