AppleInsider is confirming that Apple's upcoming Mac Pro will indeed be quad-core in at least one model. However, with quad-core on a single chip (Kentsfield) not due until Q1 2007, Apple will have to employ two dual-core chips like today's Quad.
The use of multiple processors in the Mac Pro would require Intel's Woodcrest chip. Early rumors had indicated that Conroe was on tap for the Mac Pro, but Conroe can not be used in dual-processor configurations.
Recent pre-release benchmarks of Woodcrest can be found here. Still unknown about the Mac Pro is exactly what Apple has in store for the enclosure. AppleInsider does note that recent motherboard prototypes from Intel largely mimic the size of today's PowerMac motherboards, which could indicate that an immediate departure from the current form factor is not in the cards.