AMD's 4x4 systems are only two months away, apparently. If you haven't heard of these, they are AMD's answer to Intel's upcoming Kentsfield core QX6700, which will be the "Extreme Edition" of the Core 2 Duo line. The systems, most likely very pricey at start, will consist of 3 additional FX CPUs each with two cores and with the capability of being placed in a motherboard with two physical units. The FX-70, FX-72 and FX-74 will be added at speeds of 2.6GHz, 2.8GHz and 3.0GHz. They all apparently have the same TDP at 125W, which is fairly toasty considering how well AMD has beaten Intel on the power-greediness of their CPUs the past few years.
The new motherboards for these CPUs won't be using either Socket 939 or AM2, but will require instead AMD's server line Socket 1207. This will certainly bring up the costs overall, so expect 4x4 AMD systems to cost a huge chunk of change.