Activision today announced that Call of Duty 4: Modern Warfare Variety Map Pack is now available for half-price on Xbox LIVE for a limited time. Starting September 12 (12:01 am/PDT) and running through midnight on September 14, Variety Map Pack will be priced 400 Microsoft Points. As part of the limited time offer, Xbox LIVE will also will host a Double XP Weekend, allowing players to earn twice as many Experience Points. Additionally, during the release, the limited edition Prestige gamer pics will also be made available, for free download on Xbox LIVE Marketplace. Moreover, members of Infinity Ward will also be online between noon - 4:00 pm/PDT on Saturday, September 13 to play with fans.