Woah, 34 pages devoted to the MacBook Air.... I gave up after the first 5.
Anyways I own a MacBook Pro 15", and I think the Air is cool but not for me.
As someone on some blog said, ultra-portable does not equate ultra-thin. With that kind of thickness, one probably needs to be yet another $100 computer bag which weighs twice as much as the laptop just so your precious investment don't depreciate like a rock due to scratch and bumps.
Now with the Air + protection = regular sized windows laptop that cost $500 that you won't be afraid to throw around and runs just as fast, OR a $1100 MacBook which will end up being smaller anyways.
There's definitely is a market for it, but to really reap the benefit you would probably have to be willing to put up with a thin-sleeve type protection that'll subject your $2~3000 to danger of bumps, or spend more to convert the super thin sexy laptop into a beefy package yet again.