Some time ago I checked the state of WebGL and it looked not too great. This changed dramatically recently, so I dare to say that the next browser generation coming up will change the 3D capabilities of the web this year. In the current generation (as of January 2011) there is no regular browser WebGL enabled.
Consequently, to see any WebGL demo you need a so-called nightly build. Here’s a webpage that describes where you can get nightly builds of browsers that already support WebGL (namely Webkit/Safari, Firefox and Chrome).
There are a number of 3D ‘engines’ making it easier on the web developer to include 3D artifacts in their sites. I especially came across MrDoobs outstanding blog and the three.js engine.
It fancies the ‘Or so they say…‘ WebGL Demo (video preview – must see!):
Other ways to create WebGL is to do it directly in JavaScript, of course. You will want to check out the resources on the Learning WebGL pages if you go this way.
The Cubic VR 3D engine is about to be ported to WebGL, with the fantastic (albeit somewhat older) ‘Flight of the Navigator’ demo video:
For Blender users, GLGE might be the path to take.
Also the Google Code WebGL samples are worth a look, featuring the Aquarium example that sports a winning software combination IMHO, that might make web3d finally arrive in 2011:
Posted by Dirk 
web3d-blog 