i Dont know if anyone has seen this interview however Greg Joswiak was interviewed on the powermac G5 and the G5 processor going into a notebook was brought up. Joswiak quickly replied that the amount of heat, having 9 heatsinks "probably means it wont be going into a powerbook anytime soon" The interviewer said if they were going into a notebook, Joswiak said Powerbook.

If anyone doesnt know who Greg Joswiak is, he is the Vice President of Hardware Product Marketing for Apple
You can find this video on ZDNet.com search for Mac, and its the First one named `Apple: New G5 outperforms Windows PC'