http://semiaccurate.com/2012/03/13/intels-non-delay-of-ivy-bridge-explained/
"there was a recent flap about Intel delaying Ivy Bridge chips by a quarter. As it turns out, those rumors were a bit premature....Ivys launch was delayed because Intel changed production plans at the last minute to put in a different mix of SKUs.
large parts of the Ivy die are taken up by the GPU, and there are two flavors, the 6-shader GT1 and the 16-shader GT2. Everything else being equal, a GT2 takes up notably more die area than a GT1.
If a large enough customer decides to change their orders from LV or ULV GT1s to GT2s, Intel is not going to say no to the extra revenue. And that is exactly what happened. At least one big order was moved from ULV GT1s to GT2s, and Intel could not produce enough by the launch day, so that day was moved out for all. Any guesses as to what OEM uses lots of ULV chips, has an interest in graphics that dont suck as much, and has a lot of sway at Intel?"