To be fair: I took one of the Google Chrome Experiments (can't find the exact demo right now but here's where they are hosted: http://www.chromeexperiments.com/webgl/), stripped it down, customized it (using particles instead of animated lines) and pump the geo data into the globe.

So I'd say with Three.js, Google's code for the Globe it's in the end just a couple of Javascript lines for the page and the customization of the globe. I'd say 98% is open source from a technical perspective.