PDC (front & rear) is listed as a dealer installed option in the X5 accessories catalogue (along with an option for the rear only.) The catalogue is available on the BMW website under the Owners Circle (you have to sign up if you have not already joined.)

__________________
2008 4.8i Mineral Green Metallic Sports Package, Technology Package, Cold Weather Package, Rear Climate Package, Premium Package, Premium Sound with iPod adaptor & Sirius Radio, Auto Tailgate, Head up display