I'll just leave this here...
"It is because of the OMAP4460 processor that
the Galaxy Nexus will only have the PowerVR SGX540 GPU, an antiquated beast from 2007 that can actually be found underneath the hood of last year’s Nexus S, and in the Droid Bionic.
The SGX540 is very weak compared to the Mali-400 GPU found in Samsung’s Exynos SoC (the one that powers the Galaxy S II), and it’s positively snail-paced against the Apple A5′s SGX543MP2.
What this means is that the Galaxy Nexus is going to be slightly faster than the Droid Bionic, slower than the Galaxy S II by a small margin, and significantly slower than the A5-powered iPhone 4S. The Galaxy Nexus might have a larger, brighter, higher-resolution screen than the iPhone 4′s Retina display, but it won’t necessarily have the graphics chops to actually render OpenGL games at 1280×720 at smooth framerates."
-source
About ICS, will phones with 4 buttons not receive ICS? Will there be one button that does nothing on older phones?