AppleInsider is claiming that they have confirmation that Apple will use Woodcrest processors in the upcoming Mac Pro.
The Woodcrest processor, otherwise known as the Xeon 5100 Series is said to run at speeds of up to 3.0GHz with a 4MB L2 Cache and 1.33GHz front-side bus.
This report contrasts with reports from Think Secret which state that the Mac Pro will pack Core 2 Duo processors (Conroe), but using these processors would mean a lack of Quad-Core machines due to the lacking ability of Conroe processors to run in a multi-processor configurations.