While AMD CPU's offer the best mid-range performance for the money, at the top end they aren't even in the race. In order to avoid CPU bottlenecks in later phases, with multi-GPU's, I'm gonna need the fastest chip available - and that's an Intel.
At the moment the Gulftown Core i7-980X Extreme Edition is king, but it is also very expensive. I can pick up a Bloomfield Core i7-930 for less than a third the price. It has 2 less processing cores and a lower clock speed, but it is still a socket LGA1366 chip, with the associated higher system bus speed. The necessary X58 chipset gives it access to more PCIe lanes than the P55 chipset used by socket LGA1156 CPU's - and 3-channel memory, too.
It looks like socket LGA 1366 is here for a while. All of the latest high-end motherboards use it, as do Intel's latest CPU's.
So, I'm gonna go for the i7-930 and hope that watercooling and overclocking it will let it hold up its end until the higher-end chips come down in price. If the i7-980X EE drops by just a third, over the next few months, it will pay for itself. Meanwhile, I get to spend the difference on other goodies instead - like a pair of solid state drives for the system partition, to make boot and load times fly by!