Slightly OT but in comment to what Donnie mentioned above.
I think what your going to see is a 3ghz Nehalem that is faster( more powerfull) than a 3.9ghz Yorkie,maybe even a 4ghz Yorkie.
There, I've said it and my neck is stuck out, BUT thats based on what I've seen.
Now we know a Yorkie that will do 3.9 is essentially left to the QX9650 and QX9770's..$900-1500 cpu's
Lets see what a 3ghz Nehalem sells for..