> Isn't it curious that OpenGL isn't a truly open standard at all?

As Mesa is best evidence of, the only thing about OpenGL that isn't open (also in the sense of free) is the use of the 'OpenGL' trademark. But even that can be free of charge under certain circumstances:

"Trademark License. for new licensees who want to use the OpenGL trademark and logo and claim conformance. This license is available free of charge if you are developing open source implementations on open source platforms. For closed source licenses or licenses on proprietary platforms, a charge will be associated with a trademark license."
http://www.sgi.com/products/software/opengl/license.html

MorphOS being a closed source platform means the trademark license couldn't be free of charge. But honestly, do you really think we'd need the 'OpenGL' trademark for MorphOS? I certainly don't, so Mesa would be perfectly fine for MorphOS. Of course, the MorphOS Team could as well write its own full and perfectly legal OpenGL implementation for MorphOS, but why should they do that if there's the full and perfectly legal and free to use and heavily developed OpenGL implementation that is Mesa? (That's assuming Mesa doesn't require Gallium3D, or the MorphOS Team doesn't object any longer to using Gallium3D, or they use a Mesa version prior to 7.5)