Both the CPU (with Ivy Bridge) and the GPU (with the 7000 series) families are slated for significant die shrinks soon, which should cut the heat and substantially increase battery life. Increased performance of the integrated graphics with Ivy Bridge may even allow the next 15” to cut the discrete GPU entirely for even more power and heat savings. These savings could finally allow a MacBook Air-style redesign of the 15” MacBook Pro.
Ivy Bridge probably isn’t shipping until next spring. So if you’re not in a rush, I wouldn’t suggest getting the current 15” MacBook Pro. The next update is probably going to be a huge improvement.