DICE announce day one "download content" via your VIP code when you purchase your NEW copy of Battlefield: Bad Company 2 that will unlock - as opposed to download - two maps that will be otherwise unplayable if you acquire your copy used - assuming the VIP code has been "cashed in" by then.
The code unlocks Laguna Alta area in Conquest mode and Nelson Bay - (this one looks sweet) - in Rush mode. Apparently in March at some stage you will gain access to Arica Harbor in Conquest mode and Laguna Presa in Rush mode. Without the code the initial unlocks will cost you US$15, or 1200ms (just under 20 bucks Au) but details are a fraction sketchy if you'll need to pay more for the second map pack release if you buy a used game. Reason suggests you shouldn't, but, you never know. These maps packs will already exist on the disk so the use of "DLC" is a fraction misleading.
Beats the hell out of me where you'll get a second hand copy early from anyway. Probably worth remembering this if you're considering delaying your purchase of the game.