A company called Mavizon has unveiled a new device that works with the iPhone and looks interesting called the AutoBot. I would bet a suit from Hasbro over the name chosen for the device would be coming in short order. AutoBot won't turn your new Camaro into a crime fighting robot, but it will help you find your car if you forget where you parked.
The device is compatible with "almost any" cell phone and computer out there according to the maker and will work with most cars from year 1996 and up. It will tell you when you need maintenance like oil changes and such, presumably you have to tell the thing when you changed the oil and what interval you want. It can also give you trouble codes from your car too.
The part of the system that connects to the car is a silver rectangle that plugs into the OBDII port under the steering column on most rides. The system can send the GPS location of the car to 911 and other numbers in the event that an accident is detected. It can also be used to track exactly where you car is whether it's stolen, your kid is borrowing it and you want to know where they are, and if you just forgot where you parked.