Foursquare: entertainment for users, spam for non-users. As a non-user, they provide an easy means to identify and remove people from my social networks who ar

Foursquare: entertainment for users, spam for non-users. As a non-user, they provide an easy means to identify and remove people from my social networks who are willing to spam me. Seriously, apps that send messages to non-users by default are annoying. If I cared about where you've been, I can join Foursquare on my own, I shouldn't be required to block every new app that comes along, it should be opt-in.