Todd Kopriva has an article on Premiere Pro using OpenCL on AMD Radeon HD 6750M and AMD Radeon HD 6770M graphics card with 1GB VRAM in MacBook Pro computers running Mac OSX v10.7 Awesome that they give some acceleration to non-CUDA macs since there are barely any available CUDA cards for Mac, and most Macs have AMD cards. Still they need further support in the future.
Still makes me thing that in the not too distant future a PC will be my main editing machine as it will have superior CUDA support.