Added to the X.Org Summer of Code Ideas page by Tom Stellard at AMD was an action item to add OpenCL support to the Piglit test suite, which up for now has just been testing for OpenGL conformance/compatibility with Mesa. Stellard and others would like to see OpenCL framework support to test the OpenCL API functions, a test runner, lots of OpenCL tests, etc.
There is open-source OpenCL support for Nouveau but this support for the reverse-engineered open-source NVIDIA driver is currently not mainlined. AMD meanwhile has been working towards OpenCL support in their open-source Radeon stack, but they don't have anything to show end-users at the moment.
Other possible Google Summer of Code work items include improvements to Gallium3D, Xlib, Wayland, VT switching for GNU Hurd, porting DRM to GNU Hurd, and many other items.