If you picked up the limited edition of Battlefield 3, you'll be getting the upcoming Back to Karkand map pack for free, which adds four classic Battlefield maps recreated in the Frostbite 2 engine with nice sounding things like "enhanced destruction" (bigger explosions!) and confusing sounding things like "extended persistence" (longer... longness?) It also comes with ten new weapons and three new vehicles, including buggies! There's no price yet, but it'll be out in December.