Take Apple's shipping claims with a grain of salt. A few days ago Apple emailed saying that my package had shipped, and Airborne still isn't tracking my package. So I called up Airborne, and this is evidently how it works:
The Apple Store gives you an expected shipping date. Now, contrary to reason, this is not the date when the computer will actually ship to you. Rather, this is when the manufacturer in Taiwan puts together a shipment and sends it to Apple in the US.
When this shipment happens to go out, Apple sends you an email telling you it has shipped, and gives you a tracking number -- which at this point is useless, because it hasn't actually shipped to you yet and the tracking number won't be good for anything until it does. The shipping is evidently done by some affiliate of Airborne, and as such Airborne makes no claims about how long it will take to reach its destination. In particular, at this point your choice of shipping method is irrelevant... it's still going to take a few days, maybe a week.
[Scouring the emails Apple sent you should turn up a second routing number, though it's not called that -- this is the tracking number for the shipment to Apple, and will at least give you an idea of when its moved through customs, etc.]
Eventually it will reach Apple in the US, where it will be sent out using whatever shipping method you chose. At this point, the tracking number is actually good for something (sort of... Airborne's tracking system doesn't really seem as on-the-ball as their competitors), and which method of shipping you selected has some effect.
As a point of reference, my powerbook evidently left Taiwan on Friday October 3rd. It still hasn't made it to Apple's distribution center in the US, but with 2-day delivery I'm hoping (perhaps irrationally) it will show up on October 13th.
