This summer as part of the Google Summer of Code (GSoC), a student developer was working on bringing OpenCL support to the GIMP image editing application via OpenCL support in the Generic Graphics Library (GEGL) as used by the GNU image manipulation program. GEGL has been in development for over one decade and recently has been used to a greater extent by the GIMP project. Beyond this library allowing advancements like OpenCL support, it also supports higher bit-depth images than supported otherwise by GIMP, non-destructive editing, etc.
The GEGL-OpenCL work was a fair success and using the OpenCL-ified GEGL/GIMP caused a measurable performance improvement when offloading the image work to a capable graphics processor.
GSoC has obviously been over for a few months, but there's now word that AMD is financing the student developer (Victor Oliveira) to keep working on this code. "I've been contacted by AMD and they are very interested in OpenCL adoption by the Open-Source community and want to help me to continue this project. So, I'll be continuing it as a contractor for AMD in the next few months. Of course, all code will be Open-Source. In fact, I've been developing it in my Gegl branch."
His open-source work is hosted on GNOME.org.
The developer plans to have the AMD-sponsored work complete by March and have it ready for inclusion into mainline GIMP by the time of the next release rolls around after Q2'2012 (sadly their release performance isn't the best). Experimental Windows/Linux binaries may be available prior to that.
There's no word at the moment on other open-source OpenCL projects that AMD may be sponsoring, besides the work they are investigating to have Clover/OpenCL-over-Gallium3D working for their open-source Radeon Linux graphics driver in the future.
The AMD OpenCL GEGL work was mentioned on the GEGL mailing list for developers.