High power consumption (leading to much greater total cost of ownership and noisier cooling systems), poor cost/frequency ratio, and little benefit to various existing game engines (including
UE3) make quad core not as attractive at this juncture. Sure you'll get a few more frames per second from some crappy FPS titles, but its not (IMO) worth the cost.
I think its going to be (much) more than a year before quad core starts to make sense for gaming. Its good for applications with more load-balanceable parallelization, of course.