I thought that the Apple Store would replace a defective machine regardless of where you bought it (authorized resellers, of course). I'm waiting on an MBA from Amazon. This concerns me: if I have a defective machine, is my only recourse to return it to Amazon?
Usually if it's within 14 days of purchase, Apple Stores will exchange it even if you bought it from an authorized reseller rather than the Apple Store (I bought a defective 2010 MacBook Air last year from MacMall and Apple exchanged it in store and even gave me a new receipt with a new purchase date). Beyond that, they usually send them out to the repair facility.