I get the feeling that it was pretty easy to get shipping bumped up or a free trackpad in the first 2-3 days after November 30, but it doesn't sound like as many people are having luck with that now. I got my shipping bumped up on Dec. 1. I didn't try to get a free trackpad, but I wish I had.
I called just last night and got expedited shipping and a wireless keyboard. I don't really condone trying to game this system or anything.. but when I called in to inquire about the shipping time, I just asked if they could tell me about other expedited options and if it'd be worth the money to upgrade. They just then bumped up the shipping to 2-3 day for me without even discussing any of the details. The lady did say that my BTO 27" was coming from China, so she couldn't upgrade it to next-day.
As for the keyboard, I honestly had been waffling between a wired and wireless keyboard. I ordered the wired keyboard, since it feels more useful.. but the clean look of an all wireless desktop had me in doubt. So I just asked if it'd be possible to make that change. And she told me that I'd have to cancel the order and lose my place in line. Without another word, she sent me a wireless keyboard for free.
So there it is.. Again, I think Apple's just embarrassed that they can't ship these computers out in a timely way. A $60 keyboard for free is pretty small compared to the huge margin I'm sure they're making on the iMac itself..