Well, it looks like Mass Effect 3 will have pre-order incentives. Nothing new, sure, but there will be some stuff thrown into the mix to get you to pre-order it from "here" instead of "there."
Preordering from anywhere will get you the M55 weapon.
Preordering from GameStop will get you the N7 Defender armor and the high-caliber N7 Valkyrie [Note: these are both included in the collector's edition, available everywhere].
Preordering on the PC gets you the AT12 Raider Shotgun, if if you pre-pay your membership to EA's Origin digital distribution service.
Either way you're guaranteed to be playing Mass Effect 3 on March 6th. Unless you have to work that day, in which case we'll tell you how it is.