fully spec'd 12" PowerBook?

K, first off I haven't bought one yet but I am strongly considering one.
a) It doesn't weigh more because Apple states the weight with the optical drive. Of course you if you add RAM it is going to weigh a bit more. But as far as I know humans can only tell a weight difference over 5% of the initial weight. And we're talking RAM here so... NO.
b) I heard people getting up to 5hrs. out of the battery. All depending on how you set it up(processor on high, optical drive use, airport, display, etc.) It is definitely by far going to be better than the 15". At least by 1 hour if not more.
c)It will get hotter when it doesn't stand straight on a desk or something where the heat can escape and the air can circulate. That being said, you won't burn your legs. The new ones don't get near as hot as the old ones.
I was able to check that out in a store.

Hope that helps.

You will like it...

I'm on my new 1.33 12" but I only have 768mb ram. That being said, this thing is substantially faster than my 867mhz 12". The 80gb 5400rpm drive is not audible as some users say, or maybe I am lucky. For those wondering, this is one of the new Hitachi drives, the 5k80 (Hitachi HTS548080M9AT00). I have tried this thing on reduced and highest processor settings and notice very little heat. I am typing right now on my lap and it is fine. I would say this is cooler than my rev. a 12". As for battery, I've just been surfing for the last 20 minutes, and my meter still reads 4:25 left (91%). Take it for what its worth.

Just put a 1GB module in my 12" 1.33GHz w. 5400rpm drive. I have not noticed any more heat since putting the extra RAM in. Generally the thing runs pretty cool. 80 GB drive is very quiet (much more so than my old Travelstar). I get significantly more than 2.5hrs - over 4.5 hours easily. It seems to use very little battery power when in a typing or surfing with frequent pauses (but no sleeping) work mode. Must be the processor scaling!