With the ultra portable, current ideas about what a laptop is need to be thrown out the window.
Think of it as basically an iPhone with a keyboard or better still a 2 screen clamshell. 1 screen behaves as you would expect. The lower screen becomes a configurable User input device, sometimes a keyboard, sometimes a track pad, sometimes a control wheel. The resolution of the lower screen can be much less that the upper screen just make it big enough to display a keyboard.
HDD: no way, Flash all the way.
Battery: build it in no chance to change it
Optical: not needed in an ultra portable
Ports: no thanks, they just add bulk
Wireless: every possible combination
Power: Ok I conceed that some power connection may be required.
Upgradability: not needed.
Lightness: you bet
Strength: as strong as possible. Carrying one of those bulky computer bags is not my idea of fun.
Speed: Who cares. No video editing here just internet, e-mail and all those other boring business apps.
I am constantly travelling the world for my work and my current work laptop goes everywhere with me. Even though it is one of the smallest on the market (IBM X40) 12" display, it still too heavy and too bulky. I try and avoid taking more than hand luggage with me so every bit of space that is saved the better.