Exploiting live migration
Apparently at this year's BlackHat, someone presented a paper about attacking live migration traffic. The paper describes a tool called Xensploit which uses a man-in-the-middle attack on live migration traffic to do all sorts of bad things. The core problem is that Xen live migration is not encrypted. Neither is VMotion traffic so the exploits are equally applicable.
While there's already been a lot of commentary suggesting that live migration shouldn't happen over insecure networks, that's not good enough for me. If you are sending the memory of a VM over the network unencrypted, you might as well not have any passwords on any of your machines since you are exposing all of the VM's sensitive data to anyone on the network.
For IBM Director Virtualization Manager, we go to great lengths to always ensure that Xen live migration traffic is always encrypted. As far as I know, no other Xen management tool is capable of encrypting live migration traffic. If you are using Virtualization Manager, you are protected from Xensploit style attacks.
For KVM, we were careful not to make the same mistakes that had been made for Xen. KVM supports live migration over SSH by default and provides a mechanism for third-parties to encrypt migration traffic in anyway they please.