http://libsh.org
Sh is a metaprogramming language for modern programmable GPUs (Graphics Processing Units) developed at the University of Waterloo.
Sh is built on top of C++. This does not mean that programs using Sh must be written in C++. It just means that the syntax of the GPU programs themselves will be that of C++ programs.
Sh is available for download under the zlib/libpng licence. You can check out screenshots and download sample shaders in the shaders section.