Volkswagen recently announced in-dash USB connectivity will be available starting in December with some models, and more to be offered next year. Why would you want USB in your car? Digital music players, such as iPods, are the hot new thing for vehicle. This allows you to plug right in and listen on the road without investing in a special kit or connector for your stereo.
More info in CNN articleI myself use an auxiliary connector into the back of my head unit with a small hole drilled through my dash so I can run the cable through and hook up my iPod.