One of the biggest problems with hacking the iPhone to control other gadgets is the fact that iPhone doesn’t support external devices easily without use of a middle-man computer.
When searching for solutions, some projects show up which claim that “the iphone controls my RC car/my garagedoor” etc, but actually the iphone is communicating with a pc which then again communicates with an arduino. This is ok for protyping, but I want to get rid of the PC part (Actually there was a project in 2008 which uses iphone-xbee to control a rc-car. The instructions are in Japanese, and it was made using python I believe).
For those of you who want to control peripherals directly from the iPhone bypassing a computer as a center communication hub, there’s a great tutorial that shows you how to make a serial communication device for your iPhone. From there, you can add wireless devices such as Zigbee which supports serial communications.
Check out the video demo of how this works:
As you can see in the video, this simple hack could lead to a dozen more great ideas for using iPhone as control device for many things.