After a cease and desist was issued from Google (that now owns Nest Labs, Inc.) I was forced to take down my widget. I am still not clear on the exact reason, it appears that Nest doesn’t really want any development before the official API comes out.
What is Geofencing? Geofencing is a GPS technology that draws an imaginary fence around a specified radius of your home then allows certain automation softwares to let your phone or tablet do amazing things when you leave or arrive or leave your geofence. After a very detailed discussion on how the Unofficial Nest Widget works