The Inquirer was at the launch event of the Intel Penryn CPU in Singapore and heard talks that Intel is considering to release 4GHz processors byd mid-2008:
Talking about gigglehertz, Intel has repeated that it won't slow down the Penryn frequency ramp just because of AMD's performance headaches. Even if Nehalem ends up early, as it may, there was a very quiet possibility of seeing a 4GHz FSB1600 "official" Penryn grade on future improved steppings, on both Yorkfield Extreme desktop and Harpertown dual-socket processors by mid-2008. That happens to be the expected launch date of the first dual-socket Nehalems - maybe in the Taipei June heat?
On the chipset side, the X48 spin of the X38 is pretty much ready, according to friends on the partner floor. And, combined with the QX9770 CPU or high-quality XeonUP Yorkfield variants in a month or two, you can count on very reliable everyday FSB2000+ operation - provided you liquid cool the North Bridge, we presume.