According to Digitimes, Intel will launch ten CPUs for the Xeon 5500 series with the high end topping out as a quad-core W5580 running at 3.2GHz. Processor speeds of the remaining 9 models range from 2GHz to 2.93Ghz.
Apple has traditionally used the Xeon server-class processors for their Mac Pro line. The current Mac Pro uses the Xeon (“Harpertown”) 5400 series processors and is due for an update. Despite comparable clock speeds, the Nehalem-based processors have been shown to offer clock-for-clock performance improvements up to 29%.