The next time you see "bull fight in progress", "bomb alert", "air crash", or "terrorist incident" on your traffic-update enabled GPS navigation, don't be too quick to assume that's what actually happened. Some "hackers" have discovered a way to inject RDS messages (which use the FM frequency to send traffic and weather information) into your GPS, triggering off a different alert message depending on the message.
However, since most GPS devices don't yet have traffic integration (the one that came with our car doesn't), this won't be a huge deal yet. But when these prankers find out how to inject messages that tell you there's a gigantic traffic jam on one freeway in order to move everyone to another—and thus clearing up traffic on the first—people will start to worry.
Satellite navigation users at risk for false messages [ComputerWorld]