Several sites have pointed to a Computerworld article which reports on Intel's upcoming low-power processors Merom (mobile), Woodcrest (server) and Conroe (desktop).
The article references comments by Intel's Asia Pacific sales and marketing group general manager, however, it also provides this (uncredited) tidbit:
Apple customers may be the first to enjoy Intels new CPU goodies, with the Woodcrest family of processors making it into Macintosh workstations as early as the third quarter. Woodcrest systems will be symmetric multi processing (SMP), with dual processors with up to four cores each. One such machine was demonstrated at IDF, running benchmarks under Windows XP 64-bit edition, showing eight active cores.
There have been no previous rumors about the use of Woodcrest in any Macs. Conroe has been speculated to be the processor used in the upcoming PowerMac, but at this time it all remains speculative.