A few things struck me about U.S. v. Jones.
For one thing, they never followed the path I hoped they would. The best chance for them shooting this thing down was if they determined it was over-broad. A couple of years ago, they said The Man couldn't fly around in pork-choppers scanning neighborhoods with infrared cameras looking for dope growers. The rationale behind it was that picking up heat signatures could tell you a lot more than if they're growing pot. Justice Bryer expressed concern that they could tell when he was using his Swedish sauna (rather than working). It seems the same thing applies here. A GPS device can tell when you visit the Asian massage parlor, for example. It's always on and always reporting. This goes well beyond the scope of the investigation.
Without following that avenue, I see little chance that they'll shoot this thing down. One possibility is that they overturn this guys conviction, but punt the larger issue. They were very concerned about the trespass issue. It's possible (though I wouldn't bet on it) that they conclude placing the device on his car was no-bueno, but leave the actual tracking undecided. Either way, this case demonstrates once again how completely meaningless the concept of privacy has become.
What actually concerned me the most is their opinion that this is an issue that should be left up to the legislatures. It seems to me that the 4th Amendment is actually there specifically to protect us from the intrusion of government, so it seems quite a stretch to think that the government is going to step in here and castrate itself. Their reasoning is that the people control the government, and therefore it's safe to leave the safeguard up to us, via the legislature. Of course we now know good and well that we have absolutely no control over the government. The people who actually make GPS transmitters actually have more influence than we do. Kind of a depressing situation, honestly.
In the end, I suppose that the only way this can work itself out is for the surveillance situation to get so bad that people insist something be done about it. Another entry on the list of reasons to rebel. I don't see that happening in my lifetime. At this point, I think Americans will trade all the privacy in the world for a little added convenience. Just another reason why things suck.