It has been revealed by Intel that the 3GHz Xeon processor used in the brand new 8-Core Mac Pro is an unannounced model.
Bill Kircos commented for Intel; "We are indeed shipping a 3.0GHz Xeon version [and] expect to see faster gigahertz speeds for our high-end Extreme PCs very soon, too. For now, the product is in limited production and Apple has chosen to adopt it. We will introduce another 3.0GHz Xeon SKU later on as well."
The processor is currently exclusive to Apple.