NVIDIA is in the 40% range, ATI is right above 50%. I don't think there's any light to wake up and see. Besides, NVIDIA has deals with many developers through their "The way it's meant to be played" program, where they will help with optimization and such for their cards. I've had no problems with NVIDIA cards, meaning I am not planning to switch any time soon.
Source:
http://www.xbitlabs.com/news/video/d...125134005.html