It's now clear that Microsoft wants to move x86 to iAMD64 quickly, and Intel is making more noises about getting iAMD64 parts out by the end of the summer. More reasons for would-be IPF buyers to take a wait-and-see approach, if not an outright "no thanks" approach.
Microsoft also wants into the corporate server room. IPF is its first and only path there. HP Superdome shipments and orders reached record levels last quarter and a third of them shipped with Windows. In contrast Opteron doesn't take MS anywhere it hasn't already been for years on Xeon.