Fool GPS Tracking Devices?

Ever get the idea that you're being followed or tracked by someone using a GPS device? Well, look no further than this device! I'm guessing it's suppose to jam the GPS signals and render the device inoperable. Kinda cool idea. Dunno what's the use of it, though...I mean, really, let's put it this way, if you're afraid of being tracked, you're doing something wrong. I, personally, don't care if people know where I'm at at any given time. Though I don't feel the need to be connected in any way, I don't see the reason why someone can't know where I'm at. But, I guess there are people out there that are doing the bad-things that don't want to be tracked...hahaha! Uhm, yeah...in any case, I still think this is a neat idea...though I won't condone its use, I do realize that there are people who need to be in stealth and this device might do them well...

The way this thing works is by plugging into your car's cig adapter and within seconds, it's operational. Now, it claims to only disable the GPS device that's on your vehicle and not the ones next to you...but what about cars that are close to you or devices, such as a NexTel phone, that has built-in GPS? Would this device render those useless, too, at the same time?