My down arrow key also didn't work when I got it. Took it to the genius bar and they said it should be replaced. They said they're expediting me another, but given that it's a 1.3 it appears I'm "in the queue" for another from China. Been since Sunday and no movement (online shows 3-5 weeks like a normal order but they swear to me that it's not going to take that long).
5 business days later and my replacement still hasn't shipped...called and they're quoting 7-10 business days more (i.e., the full 3 week minimum).