I'd like to warn everyone about this because this happened to my iphone over the weekend. I went to fry's electronics and was trying out different alarm clock radios made for ipods. I plugged my phone into a GPX alarm clock / ipod dock and the screen immediately went green and the phone turned off.
I took the phone out of the dock almost immediately after seeing this, but it was too late, I felt the battery start heating up inside and then the iphone got hot to the touch. After about 30 minutes the iphone no longer worked. It would not turn on or off, would not go into a restore mode. I plugged the phone into a charger and into a usb slot on a computer to no avail. I had to bring it back to the apple store.
I also got some funny looks since my iphone has "never been activated" according to their systems, but they still honored their warranty.
lesson learned, don't plug YOUR iphone into a non iphone device..