ArrayFire is a great way to supplement OpenCV for faster processing on the GPU.
Mcclanahoochie recently posted an interactive demo showing the use of OpenCV with ArrayFire for computing Local Contrast Enhancement on the GPU from webcam video.
Mcclanahoochie also shows how easy it is to convert OpenCV Mat images into ArrayFire GPU array images, as seen in the code snippit below:
All the source code is available on Google Code, linked to from his website.
Simply download ArrayFire and OpenCV and try it out for yourself!