How long before interactive ray tracing is on the desktop?

Solomon Boulos and friends in our group at Utah have their ray tracer going about 1 frame per second on one core of a 2GHz Opteron 870 with one ray per pixel at a million pixels. This is with full shadows and reflections so is slower than a lot of the numbers you see in the literature. For NTSC resolution (640x480) that would be more like 3-4 frames per second. So we'd need about 8 of those cores for fluid motion. So we are right on the threshold for such low resolutions. If Intel comes through with its 60 core chip, and ray tracing maps to it, then HDTV resolution and some multisampling should be straightforward. The Cell is also a possibility as shown by Carsten Benthin and his collaborators in their recent papers. We could get ray tracing even sooner if an ASIC is built. I don't see why a game box based on ray tracing would not be feasible now.