The current 2.8 quad that the Mac Pro uses costs about $750-$850. Apple gets it cheaper, but still.
There is no way Apple will use Beckton because:
- Too expensive ($3000+ for CPUs alone)
- Too little space inside the current case for 4 large heatsinks
- Too much power would be used (130w x 4 + 100w for mobo)
- Too much heat generated at full load in a relatively small case
- The replacement to Nehalem, Westmere, is launching within 6 months of Beckton.