To me, it's not necessarily the third-parties I'd be concerned about, but would disclosing your location to first-parties, i.e. your friends and family, be the best thing? We are all entitled to privacy of course. (Well, penumbras of privacy under the Constitution). Some choose to have Dick Cheney-like undisclosed location privacy, while others have Martha Stewart ankle-tracker privacy. But, balancing privacy requires takes a certain amount of prudence (or sanity perhaps) that will evolve as the line between public and private blurs even more. At least, at this point, Loopt allows you to opt out and only updates your location when the application is launched. What happens then you can't opt out any more? That'll throw all of us for a loop. (Sorry for the pun).