It's happened time and again in the high-tech world. When a new tool emerges, it's an exotic, high-priced item used only by a select few. The price falls slowly, until it's low enough to attract a critical mass of users. Then the bottom falls out of the pricing, and the once-exotic tool goes fully mainstream.

For example, we saw this happen recently with CD burners. In less than 10 years, CD burners went from being special-purpose units costing thousands of dollars to commodity devices that are included on most new PCs.

Today, following the same patterns, another once-exotic technology--the global positioning system--is about to go mainstream. In fact, I believe GPS technology will soon be a part of the lives of millions, especially among business travelers.

GPS technology uses a small mobile receiver and appropriate software to receive ultraprecise timing signals from a fleet of satellites (originally used by the U.S. military, but now available to all users). The GPS software processes the satellite signals to calculate the exact location of the receiver. All GPS receivers work in two dimensions (latitude and longitude) and most also work in the third dimension (altitude). Most GPS units routinely achieve accuracies to within 30 feet (10 meters) and some give accuracies within 10 feet (3 meters). If you're unfamiliar with the technology behind GPS, Trimble Navigation has a good general overview.

Unlike the bulky, expensive GPS units of yesteryear, today's GPS units are small, lightweight, and inexpensive add-ons for every major brand of PDA, palmtop, and pocket PC (Palm, Visor, Jornada, iPaq, Cassiopeia, Clie, etc.). They're also available as add-ons for high-end PDA/cell phones (such as the Nokia 92xx line), as generic add-ons for almost any laptop, and as standalone handheld or dash-mount units.

OK, But What Would You Use It For?
GPS's real power is unleashed when it's combined with digital street maps. Your GPS-equipped palmtop or laptop can generate instant, on-the-fly, turn-by-turn, moving-map directions as you navigate an unfamiliar area. Traveling with GPS is like having a live expert navigator in the seat beside you, letting you drive through an unfamiliar area with the accuracy and confidence of a local taxi driver. GPS can make missed turns--and missed meetings--a thing of the past.

Many business travelers now use printed driving directions from car-rental agencies or from sites such as Expedia, MapQuest, or Yahoo. But a traffic jam, construction detour, or any change in plans can render useless your printed driving directions. In contrast, GPS updates its location every second or so. If you have to leave your planned route for any reason, the GPS senses the change and recalculates a new route to your destination, almost instantly.

Many GPS units also continually update the estimated time of arrival so you never have to ask, "Will I still make it on time?" If you're delayed, the GPS software can show you the precise effect the delay will have on your schedule, so you can phone ahead to advise the other meeting participants of your new ETA. This lets the others do something more productive than wait for you to show up and reduces everyone's frustration with travel delays.

GPS can help in many other ways, too. For example, good GPS software comes with a built-in database of restaurants, hotels, and other travelers' points of interest, so you never blindly have to exit a highway in hopes of finding a rest stop, a place to eat, or a hotel. Instead, you'll know what's available in the area and can zero in on what you want without wasted time or travel.

Ever been scammed by a taxi driver? GPS helps ensure that any "short cut" really is a short cut and that you're not just being taken on a longer route to rack up a higher fare.

Surprisingly, GPS can help even when you're on foot. The better ones let you turn off "car" mode and enter "pedestrian" mode. The GPS will then calculate the best walking route to any destination, using shorter, more-direct courses that may not be available to cars (pedestrians aren't restricted by one-way streets, for example).