So, how does this work? Well, using cellular technology and a sensor that determines when the box is open, the USPS can provide delivery updates in a much more festive fashion than having to check your phone on computer regularly. The ornament is integrated with the existing tracking system to fetch information and flash its light the appropriate color. It can also plug into a string of lights to get its power via USB adapter.
Unfortunately, the USPS is only doing limited a limited trial this year, so you won't be able to nab one to help with your tracking duties. However, the plan is to continue to refine the device and its features, so perhaps it will be available to the masses during a future holiday season. For now, you can catch the ornament in action via the video down below.
Update: USPS posted more information here about the ornament, including how it gets power while hanging on your tree. We updated the post with that information. Despite indications that the device is ready for use on that site, we've been told there's no timetable for availability. However, by the looks of things, USPS will have the web interface ready whenever the gadget ships. (Thanks for the tip, Clint.)