Rage3D are reporting that they have been sent an OpenGL wrapper that allows Nvidia's Dawn demo to run on the latest ATI Radeon cards. Interestingly it appears to run faster on a 9800 than it does on either the NV30 or NV35 despite the higher overheads of the wrapper! It also runs with better image quality.

Dawn Sleeps With ATI

Thanks to chrismm27 for the Info.