OGRE GPL'ed 3D Engine
Steve Streeting writes "Version 0.99b of OGRE (Object-oriented Graphics Rendering Engine) has been released! OGRE is a well designed, flexible and easy to use 3D engine released under the GNU Public License. This version adds highly customisable, scriptable particle systems, generic billboard support, compatibility with VC.Net, performance improvements and various bug fixes."
JC writes to OpenGL, he does not implement it, that's the job of the driver writers. Writing to OpenGL is piss easy. Writing an OpenGL driver, or worse, a complete software implementation of OpenGL, is a fucking nightmare.