Let's hope their drivers work properly for all DX9/10/11/OGL games and applications -- though we'll need more DX11 games where DX11 mode doesn't kill performance. (Hopefully we're getting more of these this holiday season.)
Isn't the performance issue kind of up to the game programmer? DX10 had efficiency improvements over DX9 as well, but developers decided to use DX10 for all the whiz-bang effects and targeted DX9 for low-end GPUs. If developers similarly decide to target DX11 for visuals and DX9 for performance rather than also using DX11 for their Low setting presets, DX11 efficiencies won't necessarily show through.
Granted I haven't had the honors of seeing the source code for some of these fancy engines, but there is a pretty strong chance that as long as your running Vista/7, the DirectX API being used is in fact DX11, not DX9. DX11 has support for hardware downleveling, which means that you can use the 11 API with 9 class hardware, it simply disables the features that the hardware cannot handle. So why have DX9 and DX11 API implementations and switch between them when one of the two does everything the other one handles but more, and with better performance on the CPU side.
It'd be good to get a statement from Intel that Ivy Bridge will finally allow the IGP and QuickSync engine to be available even with a discrete GPU plugged in for both mobile and desktop without resorting to specific chipsets or third-party software. WIth the IGP OpenCL and DirectCompute capable, it would be useful to the the IGP help out in GPGPU tasks even if you have the latest Quad SLI/Crossfire setup.