This NVIDIA Linux x86/x86_64 driver has updates to the OpenCL SDK sample code, a new OpenCL SDK sample (named "oclsobelFilter"), an OpenCL compiler, and documentation. NVIDIA has not shared when they intend to publicly release their OpenCL Linux driver, but we would suspect around the August or September time-frame.
The Open Computing Language 1.0 specification was released last year by the Khronos Group, the same consortium that controls OpenGL plus other industry standards. NVIDIA is the first to provide hardware support for OpenCL on Linux, albeit through a proprietary driver and is currently only accessible to registered developers.
AMD is working on OpenCL support within their Catalyst Linux driver, but there is no ETA on when that will arrive in the hands of Linux customers. For open-source fans, an OpenCL state tracker is being worked on to provide this GPGPU support to hardware that has a Gallium3D driver.