There's so much misinformation and ignorance in this thread its laughable.
Completely false.
http://news.softpedia.com/newsImage/Intel-Sandy-Bridge-Review-Core-i7-2600K-and-Core-i5-2500K-4.jpg/
All of the Sandy Bridge mobile CPUs feature the high-end graphics. In fact, only the really high-end desktop CPUs have the graphics that the mobile ones do. Some cheaper desktop parts feature a GPU core with fewer units.
All the people saying that the C2D is fine, and won't be updated are missing the point. Sure, the C2D might have pretty good performance, but Sandy Bridge is irrefutably better. It has better performance per watt, overall performance, and better overall power usage. If Apple were to opt not to use a discrete graphics card in the 13" model, both power usage and physical space needed would dramatically decrease.
By using Sandy Bridge, Apple would simultaneously reduce physical space used by the processor and chipset (allowing for more battery), improve CPU performance, offer equivalent GPU performance, and lower power consumption.
Sure, Apple could stick with the C2D (despite the fact that the C2D is approaching EOL and nVidia is leaving the chipset business), but considering the overwhelming benefits, there is no reason for Apple to do so. Arrandale didn't offer compelling enough graphics, which is why Apple didn't choose to use it in the 13" model. But this time it is different.
Just because Intel had poorly performing integrated graphics in the past doesn't mean Intel will never be able to do so.
If you were less ignorant and actually looked at benchmarks you'd see that Intel's Sandy Bridge graphics are far from terrible.
http://www.bit-tech.net/hardware/graphics/2011/01/27/intel-hd-graphics-3000-performance-review/1