PC Games Hardware published some leaked slides from NVIDIA's press event that took place last week.
We already knew NVIDIA is going to heavily promote the HD movie transcoding capabilities of its GPUs through CUDA but here are some very specific numbers. According to the slide it takes a 1.6GHz dual-core CPU 10 hours and 22 minutes to encode a 2 hour long HD movie while a 3GHz quad-core processor finishes the job in 5 hours in 33 minutes.
The same 1.6GHz dual-core system with a GeForce 9600 GT will be able to complete the job in only 49 minutes! That's more than 12x as fast and the GeForce 9600 GT isn't even a high-end part. I can imagine that faster GPUs like the upcoming GeForce GTX 280 will be able to do it much faster.