>>10
A large percentage of iPhone users buys iPhones for the games (I'd say between 15-20%). I can tell from being a mobile game developer and from having seen quite a few iPhone owners in my time.
>>3,4
No shit eh? My video card does not even have geometry shaders.
There was an article a while back saying that pretty soon, all cellphones will have OpenCL, and the killer app for that will be gaming. I tend to agree. Soon you won't have specific 'shaders' anymore in a traditional rasterization pipeline; gamedev studios will just write their own complete rendering pipelines with OpenCL, and OpenGL will be dead. I don't necessarily agree that it will happen so soon, but it will happen. Here's the article:
http://blogs.arm.com/multimedia/why-opencl-will-be-on-every-smartphone-in-2014/
Desktop gaming will go the same way very soon as well. A number of people have written voxel rendering engines with CUDA (NVidia has a demo of this). id Tech 6, Carmack's game after Rage, is going to use this with raytracing for the terrain, and will render characters and such using traditional rasterization.
Exciting times!