Cloak is a new mobile app that “scrapes Instagram and Foursquare to let you know where all your friends, "friends," and nonfriends are at all times so you never have to run into that special someone.”

Funny, but I suspect the people who have enough friends on those services to make this app useful at all might be the exact types of people who would love random social encounters.

I suppose if no one wants to use the app that way they could use it as an efficient stalking facilitator: a built in pivot.