Apartm.net's 2011 New Year's Eve invitation takes it to a whole new level
Come to our New Year's Eve party. Check in with Foursquare to apartm.net, and the door opens automatically. Stay until 4 am in the new year. See you there.
More details can be found here: apartm.net/newyears/2011.
Details about the hack can be found on the apartm.net/door page.