Mercury Graphics Engine
Starting with Adobe Photoshop CS6, there is a new Mercury Graphics Engine (MGE) that will use your video card's GPU to improve Photoshop's performance. This new Mercury Graphics Engine will provide near-instant results when working with certain key tools, such as Lighting Effects, Liquify, etc.
The best thing about the Mercury Graphics Engine is, it uses both OpenGL and OpenCL. Which means, you do NOT need a CUDA enabled video card from NVidia.
Let me repeat that, Photoshop CS6 itself, does not use CUDA, it uses OpenGL and OpenCL for GPU acceleration. So there are no hacks, mods, etc. to get your video card to work. All you need to do is setup PhotoShop CS6 to your your video card.
This means, you can use pretty much any of the newer video cards from AMD/ATI, Intel and NVidia. However, keep reading. There are some things you are going to need to know.
NOTE: There are some 3rd party plugins for Adobe Photoshop that use the CUDA technology. If you use any 3rd party plugins that use the CUDA technology, then you will need a NVidia graphics card.