Yeah, I did see a news blurb a while back with the company who had some of their employees (voluntarily) have subdermal chips implanted. Theirs (I think) were mostly used as a company id card and accessing company facilities & services rather than being used as locators/trackers. But how long until such things are used for tracking? I just don't see how the minor benefit of having an ID you can't lose makes up for that potential loss of privacy.