During one of the many presentations during IDF Taipei, the slide below was shown and as you can see, it has to do with Core i7 memory support. The odd thing is the last point, Population rule, as according to it, you have to fit the memory modules in a specific order.

The issue here is that you have to populate what Intel refers to as slot 0 in each of the channels first, as otherwise the system won't recognize the memory. This shouldn't be too much of an issue, unless you're using some exotic kind of CPU cooling that takes up too much space and prevents you from putting your memory modules into those slots.

This is all related to a minor bug or errata, as Intel likes to call it, in the first generation of Nehalem/Bloomfield processors, but it should be rectified down the road as Intel didn't have enough time to fix the issue straight away.

One thing that might disappoint some is that the desktop Core i7 processors will only support unbuffered DIMMs, unlike the Xeon counterparts, so despite the fact that the Core i7 might be an ideal workstation platform, some might shy away from it due to the lack of buffered memory support.

This slide also confirms the official 800 and 1,066MHz memory support, although it's possible to overclock the memory much higher than this, thanks to the unlocked memory multiplier across the range.

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Core i7 has unlocked memory multiplier