So on Christmas Eve I was tracking Santa (as you do), and noticed that the NORAD tracking no longer opens up Google Earth, but instead works in browser.
Doing some digging around I found that they used Cesium. This uses WebGL to create 2D maps and 3D globes. From the start of ArduPlotter there has been a button to download a (generated) KML file of the flight which will open in Google Earth if you have it installed. Being able to view a 3D map in browser seemed like an awesome idea, so I set about making a quick prototype.