The current demo uses few features, there is multitexturing (no dynamic lighting yet). I tried to implement the shader compositor like Roland submitted into OpenSceneGraph. My implementation is quick and dirty, so a lot of improvement will come soon.
To get a WebGL Implementation have look to Khronos instructions http://www.khronos.org/webgl/wiki/GettingaWebGL_Implementation
You have a browser that is able to run webGL try the realtime version http://plopbyte.com/webgl-openscenegraph-demo