Laughs. It's a fancy design product, of course it's going to cost more. What do you expect? If you could make think computers out of normal components, then they all would be as thin as the Air, right? And the point of making a thin notebook computer is simply to have a product with something special, and that luxury is what you charge extra for.
You can think about it in the terms of basic marketing - people are willing to pay more, since they see a certain product is actually worth more than the value of it's parts. This is called putting a pricetag on immaterial value. You probably do pay extra, too, when you buy a Fender product for example. A Fender isn't actually much better than the rest of the basses in it's price class (let's think about MIM Standard basses that might be actually poorer than the competition) but you think "it's a original Fender" and dump the cash on it - you are not only paying for the bass guitar parts it takes to make it, but also to get the Fender brand, represented by the Fender decal on the headstock.
In the similar matter, you are paying for extra value on a Air, and that extra value comes from the thin design, light weight etc, and partially from uniqueness. Actually, not in case of the Air, but luxury products as a whole, high price itself can be a value too, since you get to show off your wealth and know that the average person probably can't afford a similar product.
And so, if there are people who are willing to pay to get a luxury product, you make one and sell it to them. That's why you have stuff like Bentley, Rolex and Louis Vutton, or builders like Ritter around.
I wouldn't be surprised if Apple didn't make too much profit on the Air - the marketing value alone is huge. It's a highend product that they can use to stand out from the crowd and to generate market buzz. Just think about the tons of internet discussion it has generated - we're even talking it right now, even though it's been on the market for months!