Software for GPUs inc. compiler/directives, maths libs & tools (debuggers and profilers)
OpenCL™ is the first open, royalty-free standard for cross-platform, parallel programming of modern processors found in personal computers, servers and handheld/embedded devices. OpenCL (Open Computing Language) greatly improves speed and responsiveness for a wide spectrum of applications in numerous market categories from gaming and entertainment to scientific and medical software.
Khronos - the home of OpenCL
Nvidia OpenCL home page (part of CUDA toolkit)
Nvidia CUDA 4 + OpenCL and driver download page (install the CUDA toolkit which includes Nvidia's OpenCL files).
GPUs at The University of Manchester
Getting Started and Tutorials
List of OpenCL tutorials inc. online tutorials
Nvidia has a document giving details of some of the differences between CUDA and OpenCL at http://developer.download.nvidia.com/OpenCL/NVIDIA_OpenCL_JumpStart_Guide.pdf
Introduction to GPU Programming with OpenCL course materials developed by Simon McIntosh-Smith (Bristol) delivered as a two day training course for HECToR at NAG offices. Makes use of NVIDIA's OpenCL SDK.
The OpenCL Programming Book by FixStars now released in HTML format
The University of Manchester runs an OpenCL module as part of its GPU courses. More information on OpenCL is available there.