Apple's early portables didn't push the technology envelope, and didn't have to. Windows portables all ran the same software, so they had to compete on the basis of hardware features. Most Apple users picked it for its software. As long as the hardware was within shouting distance of the state of the art, that was good enough.

Later Apple began to pioneer in hardware design: first 17" laptop, thinner than the competition (though not necessarily lighter) and so on. This got them some converts, people who chose them for hardware features but who otherwise wouldn't have. They saw a market opportunity and decided to follow it.

The MacBook Air continues that trend. Will its unique hardware aspects appeal to everyone? Of course not. Have any of them appeared in other systems? Of course. Do other companies make sub-notebooks that appeal more, on balance, to some users? Of course. But all that said, the package is unique and will do more than simply retain the fanboys who want something along these lines. None of the negative posts in this thread, most of which are factual or at least have a foundation in fact, will change this. The MacBook Air doesn't have to meet everyone's needs, or appeal to everyone for any reason at all, for that to happen.

(Truth in advertising: I have not placed an order and don't plan to. I have a personal 17" last-generation PowerBook and a long-term employer loan of a 15" recent MacBook; I don't have a problem with their size or weight.)