KVM was announced a few months ago, it’s already in the Linux kernel and now has live migration:
On the other hand, KVM appears to be on the fast path. This project first surfaced in October 2006; it found its way into the 2.6.20 kernel a few months later. On 25 February, KVM 15 was announced. This release has an interesting new feature: live migration. The speed with which the KVM developers have been able to add relatively advanced features is impressive; equally impressive is just how simple the code that implements live migration is.