In other words, yes the MP is more powerful than the xserve, individually, but *not* the way a machine room usually is deployed.
Actually, the Mac Pro is not more powerful than the Xserve. The only problem with this last refresh of the Mac Pro in August is that they didn't also refresh the Xserve. For the rest of its life, the Xserve has always had the capacity for the same number of cores and RAM as the Mac Pro.