May 1, 2000 marked a point in history that changed the future of GPS. On that day, some 10 years ago, President Bill Clinton approved the unscrambling of military satellite signals. This decision paved the way for civilian use of GPS, allowing them the same level of accuracy as the military.
In the last decade GPS technology has seen exponential growth, evident when comparing extremely basic units from days gone by, to the GPS-enabled smartphones of today.
With so much change one wouldn't expect to see people using the older GPS units, but due to the simplicity of their interface and the same coordinate system, there wasn't a need to upgrade. Now saying that, upgraded units do offer benefits over the 1st generation GPS models. Features like mapping and USB computer interface are not available on the older styles, so upgrades are neccessary to keep up with the varying use of GPS.
With the gained access to the military satellite system, consumer-grade GPS accuracy increased from 100 yards to 10 yards, quite a significant jump. The advent of geocaching came about at the same time, since treasure hunting for a small container, in an area with a perimeter of 100 yards, was a bit tricky.
GPS technology is bound to make many more advancements in the coming years, but surely none that will have the same impact as offering the satellite signals to anyone and everyone.