Here's an enthusiast demonstrating his prototype of what you can do with an iPod Touch and some computer skills. He can control his Mazda from anywhere in the world (not show, he even has a camera in the car, and it sends images to his Touch.)
Apple's minicomputers, the iPhone and the Touch, will completely change how we interact with our "intelligent" hardware. At the Apple applications store there's a deluge of ingenious apps presented daily, as people around the world are designing solutions that were impossible just months ago.
But here's the car and the iPod Touch: