The CRIU project has been busy and it seems live migration for LXC containers could be a reality very soon. Serge Hallyn - one of the developers of LXC for those who don't know - reports checkpoint/restore and live migration is on the way.

Live migration is used with virtual machines to move workloads across systems with minimal disruption.

CRIU is a project to implement checkpoint/restore functionality for Linux in userspace. An enterprising user seems to have a proof of concept working already.