Mac Performance Guide has a new test showing a MacBook Pro vs a MacPro doing h.264 encoding. The MacPro has a consumer CPU which has QuickSync. Now you have to do specific encoder settings to get this result, but it clearly shows the MacPro being thoroughly beat by the MacBookPro!
It is pretty idiotic that Intel would actual have better features in their consumer chips than their much more expensive professional Xeon chips! Really for most uses the Xeon is really best because you can have more cores and you can have dual processors, but since you can get higher core i7 chips now, maybe a hackintosh with a Core i7 would be better in many circumstances!