Thanks Garteal and TechSpot: http://www.techspot.com/news/54134-amd-launches-mantle-api-to-optimize-pc-gpu-performance.html
Why a new API instead of OpenGL you ask?
TechSpot said:We've been told at the GPU14 Tech Day event that the Mantle API is open, so theoretically Nvidia could purpose the technology in their GPUs. It should also make cross-development between PC and console games a lot easier, and also more incredible for those with a high-performance AMD GPU.
More information on Mantle will be available at the AMD Developer Summit in November.
Why a new API instead of OpenGL you ask?
So... they created another open API. Is OpenGL too much of a clusterfuck for them to commit to the established open standard?
Using OpenGL would have been a downgrade from using DX11 and we wouldn't solve any of the problems that I mentioned on my slide about what challenges we have on PC. Hence Mantle is needed.