Someone just posted this to the OpenSceneGraph forums. Evidently Google released O3D a couple weeks ago - it's a plugin for loading 3d content in a browser, and it uses Javascript to drive the interaction. On the surface, it sounds conspicuously like C3DL, another browser plugin for loading Collada models. Read a little further, you'll see there are some technical differences, but even if there were not technical differences, the advantage would go to any product from google. At least until Firefox gets native support.

I tried google's plugin with Chrome on my work desktop, their complicated sample gets about 4 fps, but I don't think my graphics card does shaders very well. The simple cube renders a lot faster.

Here's their demo video:

The advantage over Papervision or other flash-based code is that they can use DirectX hardware shaders. The disadvantage is having to install yet-another plugin.