You don't need PCIe 3.0 yet any way. They haven't even made a good reason to go beyond 8x PCIe 2.0 (multiple tests available online showing single and multi-gpu configs in 4x 8x 16x and mixed in between). Difference between 8x and 16x is less than 5fps on high end rigs.
Now maybe for things like specialist add on cards or SSDs, but that's what on board SATAIII is for
At least on existing chipsets SATA 3.0 steals PCIE lanes from your graphics card(s) when run in 6gbs mode.
Also after doing some research on this it seems that you might take a performance penalty for running 32nm quad core chips on existing 1156 and 1155 chipsets because DMI is supposed to have twice the bandwidth on Sandy Bridge. If it is in fact backwards compatible then the DMI interface will have to run at half speed on p55/H55/H57 chipset.
If this turns out to be the case I'll probably just built a new kickass PC next year and relegate my current machine to a backup PC.
EDIT actually you shouldn't unless you care about 6gbs SATA 3.0 Edited, Aug 31st 2010 10:40am by Lobivopis