Some weeks ago the SICG had announced their first compositor for Blender with OpenCL acceleration.
The compositor is currently in an early development status and the devs are looking for tests and feedback, later versions may be integrated into the stable blender tree.
A scene on the test system from the developers (Intel Core i7 with NVIDIA GT 220 graphics card) was processed nearly 10 times faster when using the GPU acceleration instead of the CPU processing.

The usage of OpenCL acceleration in this version is limited to the defocus node, blur node, color balance, lens distortion, brightness, rotate and tonemap.