Fun fact: GPS technology has built-in limits based on speed and altitude. Basically, if a vehicle is moving faster than 1200mph or cruising higher than 60,000 feet, GPS shuts off. Why those numbers exactly? You can thank the commies.
The CoCOM, or Coordinating Committee for Multilateral Export Controls, was established in the early years of the Cold War to put an arms embargo on Eastern Bloc countries. After GPS was developed by the Defense Department, COCOM limits were put in place so that the government could be sure the technology wouldn't end up in commie-guided missiles.
Of course, the Cold War is over. That your GPS stops functioning when you're moving that fast or that high (which is to say not often) is because it's a relic of a bygone age. [Wikipedia via MAKE]