We understand that these are to be called, rather straightforwardly, "Prescott New Instructions" and rather than necessarily being linked with any speculative "Yamhill" X86-64 part to the core, are instead intended to take adventage of hyperthreading in the new processor.
But so far we know little about what form the "Prescott New Instructions" (PNI) will take, or how many of them there will be.
Nor are we yet aware of whether or not Intel will allow others, like it did with MMX, SSE or SSE2, to license PNI.
Whatever the nature of the new instructions, we can speculate with some degree of certainty that the Alpha engineers Intel acquired from Compaq sure had some good hyperthreading tech built into that microprocessor, and we wouldn't be a bit surprised if PNI owes more to DEC than anyone could ever have imagined even a year ago. µ