As iPod integration becomes a standard option, the iPhone is next in line for car-audio upgrades. Mercedes is preparing to offer a $400 iPhone integration as an option on 2009 model-year cars, according to Leftlane News. First announced last week, the device is an iPhone cradle integrated into the console between the driver and passenger seats, and can be operated from the car's steering wheel-mounted controls. The cradle should offer full connectivity to all the iPhone's audio options. A retrofit for older Mercedes models will also be available. It is expected in August for about $400.