QEMU 1.2.0 improves live migration
Among the new features of version 1.2.0 of QEMU is support for passing through PCI devices to hardware-virtualised Xen guests. The open source system emulator is used in both the KVM and Xen virtualisation platforms, but can also be used independently. The new release can migrate active guest systems to different hosts (live migration) even if the guests use USB storage media and pass-through devices. In addition, live migration is said to be more reliable for guest systems that use large amounts of RAM.
You don't need to be a genius to debug a pf.conf firewall ruleset, you just need the guts to run tcpdump