Activision today announced that Call of Duty 4: Modern Warfare Variety Map Pack is now available for half-price on PlayStation Network for a limited time. Starting September 18 and running through 2:00 pm/PDT on September 25, Variety Map Pack will be available for $4.99, down from $9.99. This offer is not available in Europe at the present time. As part of the limited time offer, PlayStation Network will also host a Double XP Weekend, allowing players to earn twice as much XP. Members of Infinity Ward will also be online between noon – 4:00 pm/PDT on Friday, September 19 to play with fans.