We are looking to build a strong community around Cesium, and are interested in collaborating with potential contributors and users. Don't hesitate to email me.
For more information beyond the demos, check out my WebGL Camp Orlando talk, WebGL for Dynamic Virtual Globes [pdf]:
We have ported parts of our book's engine, OpenGlobe, to Cesium. In particular, the Cesium renderer and polygon pipeline are quite similar to OpenGlobe. In some ways, Cesium is our next generation version of OpenGlobe.