From what I can gather, it's like a 3-d canvas. I havn't had a chance to install yet.... alot of dependencies....but it appears to be a "layered 2-d scenegraph", where multiple 2d canvases are layered to give a 3d effect. The canvas aspect supposedly gives you persistence of objects. Essentially, it should allow you to program a 3d canvas.

I probably won't get to testing it until later this month.