This simple cigarette adapter plug-in reportedly "knocks out GPS logging or GPS tracking systems that may be operating in your vehicle," and considering that it sports a two-to-four meter operating range, just about every automobile outside of an 18-wheeler (or limousine) should be covered.
If you're the type who just may be the victim of undercover GPS tracking (read: promiscuous), you should give some serious thought to this one.
Unfortunately, there's no word yet on how much this potential life-saver will cost, but its slated to ship "soon" to the devious and uber-paranoid sects.