The initial batch of C1 revision Sandy Bridge-E processors have a bug – “errata” in Intel terminology – in them with VT-d, which means that hardware accelerated virtualization doesn’t work properly with them (software only mode is unaffected).
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Intel will only certify the Waimea Bay platform for PCI Express 2.0 at launch, since there aren’t enough third party cards to test with. Some PCI Express 3.0 devices are still likely to work, but Intel doesn’t guarantee compatibility. This doesn’t bode well for the current 6-series motherboard with gen 3 switches actually working properly once cards and especially, Ivy Bridge processors arrive. Waiting for full qualification before purchasing is therefore advised, or an expensive motherboard replacement may be required in the not too distant future.

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It’s not so good on the chipset front, either. Intel has increased the price of the X79 chipset by 20% compared to the X58 chipset, putting the X79 chipset somewhere in the region of $70. This is the list price, so the discounted or “street” price should be a lot lower. However, we are looking at a chipset that offers no new features over X58 and it’s the same size as the 6-series chipsets – it should be cheaper to manufacture than the X58 chipset which only consists of the I/O Hub and the ICH10R.

LOL.. it makes me happy with my X58 rigs

However, i *hate* the lack of progress with Intel and the 8x+8x PCIe lanes, the lack of USB 3.0 and no official PCIe 3.0. Not to mention their memory and bandwidth limitations. Their MBs suck compared to the AMD (feature-wise; i can't say much for my new ASUS AM3+ as it refused to post yesterday and i ordered a replacement).