Two new questions arise, courtesy of the latest advancement in cellphone technology: Do you want your friends, family, or colleagues to know where you are at any given time? And do you want to know where they are?
But such services point to a new truth of modern life: If GPS made it harder to get lost, new cellphone services are now making it harder to hide.
"There are massive changes going on in society, particularly among young people who feel comfortable sharing information in a digital society," said Kevin Bankston, a staff attorney at the Electronic Frontier Foundation, based in San Francisco.
"We don't know what the implications are," he added. "We seem to be getting into a period where people are closely watching each other, and there are privacy risks we haven't begun to grapple with."