According to
HKEPC, Intel has decided to postpone by a couple of days the official launch of its new desktop CPU: Conroe, a.k.a. Core 2 Duo; it will be on July 27th instead of July 23rd.
The Core 2 Duo will probably find its way in a new version of iMac and Mac Pro (successor of the current PMG5).
For the Mac Pro, Apple could use the Core 2 Duo for the Mac Pro entry level models. There is no motherboard able to be equipped with 2 Conroe, so a Conroe-based Mac Pro will be a double core single CPU, so it can not really compete with the current PMG 5 Quad. So, one should see the Xeon WoodCrest in high-end Mac Pro, and maybe Conroe in the entry levels; but all models of Mac Pro could be also be powered by Xeon WoodCrest, depending on original plans.
(Unlikely for us that Apple uses 2 different CPUs/sockets for the Mac Pro line).