The Pentium 4. Hot. In more ways than one, for sure. The Prescott and its Dual-Core variants are veritable toasters. So, it makes one wonder why Intel would want to switch to a move to rate processors by their power efficiency rather than clock speed. A while back the Tejas core was cancelled, which would have let the P4 scale to over 5Ghz. And now this:

"It's not even so much even performance per watt as it is fitting higher performance computing into more constrained environments, either constrained by power, by [heat] or by noise or size,"
This may sound likes news, but we've heard this before. Intel was the first to say that clock speed wasn't indicative of performance. Then again, they also bled that clock-speed rush for all it was worth. With AMD processors again and again being more power-efficient than the P4 and Xeon, it seems a bit ironic they would now be pushing a matrix-style efficiency scale. It makes you wonder what Intel has under their sleeve. Perhaps we'll see another "Centrino".