The new Mac Pro desktop machine ships with 2x dual core Intel processors, which by itself really is a monster of a machine. Later this year though, Intel will be shipping quad-core Xeon and Core 2 processors. A pair of these in a dual processor machine like the Mac Pro will give you 8 cores. Yes, 8.
AnandTech have a review on their site where they obtained a pair of these new CPUs and installed them in a Mac Pro, and confirmed that yes, Mac OS X on a Mac Pro will recognize and run with 8 cores. Now that’s some horsepower.