Welp! You'll be waiitng a looooooooong time.
Amazon has officially reported that, for unknown reasons, the release of the Servbot Head and Ijiek Jacket items for your Xbox 360 avatar have been delayed. Indefinatly. No reason was ever given as to why. Originally, Amazon offered $10 store credit for the initial delay.
However, due to the cancelation of this pre-order bonus, those who pre-ordered the Xbox 360 version of Dead Rising 2 from Amazon should have now received an e-mail offering ANOTHER $10 in store credit and 50% discount on Marvel vs. Capcom 3: Fate of Two Worlds for your trouble.
I do not beleive this affects anyone who pre-ordered the PS3 or PC versions of the game.
Source: Game Informer
EDIT
I just have to point this out: Marvel Vs Capcom 3 (Xbox) is currently 57.99 on Amazon.
That %50 off deal will take the price down to $28.99.
Add the store credit you also got: $18.99.
Add that other $10 store credit: $8.99
Add the $10 credit you got for pre-ordering MvC3 on Amazon anyways: -$1.01
So if you pre-ordered the Xbox version of Dead Rising 2 on Amazon, That means you can get MvC3 for NEGITIVE ONE DOLLAR ON RELEASE DAY.
Now that, my freinds, is a DAMN good deal.