I may be crazy, but I've been thinking of selling my 667 DVI Powerbook and buying a 12" 900 MHz iBook. I use my Powerbook 99.9% of the time on my lap, and the heat and weight are factors in my computing enjoyment. I really only use it for web surfing, email, and some Word/Excel type of stuff, so the speed of the Powerbook isn't really an issue with me.
One BIG factor in making this decision is if the new ibooks are cooler than my 667 DVI. Has anyone experienced both?