It's not like 1,600MHz FSB CPUs will be saved for X48 either, since Asus has already added support on its X38 boards. If Asus can manage this, we have no doubt that everyone else will follow suit too, which in turn kills any potential hardware leverage the X48 might have had.
On the overclocking front, Asus has shown me that it has achieved 568MHz FSB with an E6550 on air with a moderate voltage increase, however the team behind that must have a gem of a CPU because I can only get our QX9770 processor to match the results we got with our P5E3 Deluxe, which topped out around 500MHz FSB.
If you've already bought an X38 then don't stress about X48 - you're already there, just keep your BIOS up to date. However what worries me is that since X38 is hardly the performance demon what we expected it to be over P35 - where does this leave Intel's mid-to-high end chipset business?"