I started chatting with an 80 year old neighbor of mine the other day and she'd just gotten a new car and they tried to talk her into the Onstar type program. She said "no way am I giving the government my location that way" and the saleslady said "but it'll be so much safer for you in an accident." And my neighbor reiterated that she didn't want to volunteer for having her every moved tracked by the authorities. The saleslady tried again with, "oh, I don't think people have the time to track everybody". Her reply? "George Bush does. He's got plenty of free time as far as I can see. And I don't trust him."
She also gave me a glass of water because it was hot as hell out and I was on a run.
Of course eventually all cell phones will have GPS positioning which means you can be located with that too. I just keep thinking about all the changes I would have to make to stay beneath the radar. I don't use cash much - everything is bought with credit cards because it's safer, but someone now knows my spending habits. It's definitly something to think on though, this ability for someone to track you on a whim.