I'm using it successfully with Lutron HomeWorks to trigger a "Home" which turns on some lights when the Homeowner arrives and it's dark outside.

Had to do some creative stuff so I could apply variables to the event that's triggered by the geo fencing, but it works well.  The only property I've had problems with is in a really poor cell area and the phone doesn't always have enough signal to trigger the geo fencing event reliably.