Jeff Campbell talked about this topic a bit on the earnings call. The way it sounded, financing with Boeing is already in place for all of the deliveries. While there won't be any cash out of pocket due on delivery, AA will still be making payments on them. If we default, Boeing gets them back, rather than a bank or a leasing firm like ILFC.
The Boeing deal does require advance notice, which is why these 11 weren't able to be deferred, but those due for delivery later in 2003 and in 2004 were able to be deferred or cancelled. I'm sure AA tried to get someone else to pick them up (similar to the 737-800 deliveries last year -- they all went to QF), but there simply isn't any demand for widebodies right now.
Also, there were deposits and progress payments paid on all 9 deliveries, so if AA walks away from the aircraft, even in Ch.11, they would be foregoing those payments as well.