Is that much different than what Facebook or Google Maps are already doing behind the scenes? They might not make that data accessible to you, but it's undoubtedly being (or able to be) compiled behind the scenes. See this update:

http://techcrunch.com/2015/07/28/google-search-now-shows-you...

The average HN user might not care for such a system, but I think many people would find it reassuring for better or worse.