go Gaming Platform and link your PSN to it then in your email inbox should have somthing like this "If you link your Shift account to Borderlands 2 from within the game (Main Menu -> Extras -> Shift Code) a Golden Key will be automatically added to your in-game inventory – you can use it to unlock a rare item in the mysterious Sanctuary loot chest. This will happen automatically with no code input required -- it's a pretty cool deal!".
Or go check in-game, I cant confirm this cuz I dont have BL 2, but I just registered, hope someone who has BL 2 confirm this for me.
Edited by kingcz, 20 September 2012 - 12:57 PM.