I got a confirmation email it says
PRO TIP: 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!
But no code. also cannot connect my shift account to my xbl apparently feature unavailable is this because im from UK and its not officially out yet or is it just not working