In-vehicle GPS navigation has come a long way in a very short time. Remember when turn-by-turn navigation for your truck cost $2,000? Well, you can still spend that much or more for an installed system with an in-dash screen - but, increasingly, the market has followed portable nav pioneers Garmin and Magellan and other companies with portable systems that are much less expensive. While portable navigation units aren't as compact as a handheld unit, you can transfer them from one vehicle to another and get almost as many features as with an in-dash model. Plug the power cord into your cigarette lighter, stick a suction cup mount to your windshield, and you're good to go!

One note of caution, however: This field is changing rapidly, with lots of new players entering the market, declining price points, dueling cool features (media players, Bluetooth, etc.), and emerging platforms and technologies waiting in the wings. I asked the marketing director of a portable nav manufacturer when we'll start to see turn-by-turn competition from cell phones and he replied, "In about two minutes!" But that's no reason to hold off buying, because portable nav is very cool and useful. It has officially reached the mainstream, and once you have it onboard your truck, your nav system will become part of your everyday routine.

Clarion calls its portable nav units NICE, which stands for Navigation In-Car Entertainment. The NICE P200 features a 4-inch touch screen, a built-in rechargeable battery, a 20GB hard drive with maps of the U.S. and Canada, and a USB 2.0 port to allow the unit to interface with a computer. Aside from turn-by-turn directions and two million points of interest, it can store and play music, DivX video, and digital images. MSRP $900.

The Garmin StreetPilot c550 comes with a slightly different feature set than the Clarion piece, so be aware that when you shop for portable GPS you will definitely need to take apples and oranges into account. The c550 comes with the complete U.S. and Canada maps onboard (plus Puerto Rico), but it also boasts two very cool features: Bluetooth for hands-free phoning (Bluetooth phone not included), and a three-month trial subscription to live FM traffic. No word at press time on how much live traffic will cost you after the trial period, but I'm guessing you'll be seriously addicted by then. MSRP $857.

The Magellan RoadMate 3050T offers complete U.S. and Canada maps (plus Puerto Rico), over six million points of interest, a three-month trial subscription to live traffic, a music player, and a picture viewer. One nice feature is the integrated battery that allows you to explore the next day's driving route from the comfort of a hotel room. MSRP $649.

Pioneer's AVIC-S1 is a compact unit that also lengthens the umbilical chord between itself and the cigarette lighter, acts as a Bluetooth speaker for your cell phone, and exchanges address book contacts with your phone. Not to mention that it also gets you from point A to point B. MSRP $599.99

We'll continue to keep you informed about this red-hot product category.