[elihu]

Ray tracing has other advantages besides shiny reflections: it can handle refraction, shadows, non-triangle-based geometric primitives (including CSG), and has less sensitivity to the total amount of geometry in a scene.

Global illumination is where we want to go to surpass the realism of current games, but path tracing and photon mapping are both fundamentally based on ray-tracing. Any hardware that makes ray-tracing go faster (especially for incoherent rays) should also help to speed up global illumination.