In the Top Gear San Franciso to Bonneville road trip, one of the driver's played a nasty trick on the Challenger owner. While he was eating lunch, the other driver sneaked out, started the SRT with the push button, and parked it in the middle of the right-hand lane of the highway. Apparently, the key fob (in the owner's pocket) was close enough to allow the car to be started.
When the British driver/owner came outside, he was startled to find that his car had moved from the parking lot to the highway. I assume that if the "thief" had continued to drive the car it would have cut-off. Right? That's why I always lock my car and have a Revelco Anti-Theft device.
The segment about the key fob is 4:26 minutes into the video. See:
http://www.youtube.com/watch?v=iqzJn0p6MM8