PC Perspective had a chat with NVIDIA's Chief Scientist David Kirk about Ray Tracing and Rasterization. Here's a snip:
PC Perspective: While the benefits of ray tracing do look compelling, why is it that NVIDIA and AMD/ATI have concentrated on the traditional rasterization architectures rather than going ray tracing?
David Kirk, NVIDIA: Reality intrudes into the most fantastic ideas and plans. Virtually all games and professional applications make use of the modern APIs for graphics: OpenGL(tm) and DirectX(tm). These APIs use rasterization, not ray tracing. So, the present environment is almost entirely rasterization-based. We would be foolish not to build hardware that runs current applications well.
Ray tracing may be the future of rendering—it’s definitely part of the future at least. There is an old joke that goes "Ray tracing is the technology of the future and it always will be!". I don't think that's completely true, but I do believe that ray tracing is not the answer—it's part of an answer. Furthermore, I believe that the C/C++ language programming interfaces for GPU computing are useful for programming ray tracing to run on GPUs. Over time, I expect the graphics APIs will evolve to embrace ray tracing as part of the 3D graphics "bag of tricks" for making images.