Nick Bilton writes on bits:

…“Hey, I see you’re having people over. O.K. if I stop by?” read a text message from someone whom I had not invited to my place for a dinner party.

How did the person know I was even having a party? I needed only to glance at my guests, who were sharing messages and photos of the dinner to their online social networks.

Serendipitous discovery, or uncomfortable situation?