The iPhone is steadily becoming like a universal remote, what with applications like this Viper SmartStart system that allows users to unlock and start their cars sans keys.
For $500, which is the price of the Viper SmartStart receiver (the actuall app is free on iTunes), the system will unlock, start, set the alarm, and unlock the trunk of your car. It will also allow you to find a misplaced vehicle via a ‘panic’ button. Basically, it’s like any old remote car starter, except it will be part of your iPhone. You have the option, however, to manage more than one car with it as well as assign more than one user to the car.