Imagination Technologies, which was responsible for the PowerVR SGX GPU chip in the iPhone 3GS, just announced the next version in the same line. Hence, this might be the next-gen iPhone GPU. And it's a nice chip.
The PowerVR SGX545 (iPhone 3GS had the SGX535) has OpenGL 3.2 and Open CL 1.0 support, runs at 200MHz and can even do "HD" output. It can even support DirectX 10.1. Here's the full support list:
* DirectX10.1 API support * Enhanced support for DirectX10 Geometry Shaders * DirectX10 Data assembler support (Vertex, primitive and instance ID generation) * Render target resource array support * Full arbitrary non power of two texture support * Full filtering support for F16 texture types * Support for all DirectX10 mandated texture formats * Sampling from unresolved MSAA surfaces * Support for Gamma on output pixels * Order dependent coverage based AA (anti-aliased lines) * Enhanced line rasterisation
There's no guarantee that this is the chip that's going to be in the iPhone 3GSS, or iPhone 4G or iPhone 3GVideo, or whatever, but it's a good next step. [Apple Insider]