Go look it up, OpenGL isn't a free "do whatever you like" setup. There is licensing for it for companies like nVidia.
I decided to do exactly that. This is from their licensing website.
The following are the currently available licenses:
Open source license, for use of the S.I.. This is a Free Software License B closely modeled on BSD, X, and Mozilla licenses.
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.
Emphasis mine. There's also a note on the page that former licensees can open source their code and no longer need a license. If you're making an open source implementation, OpenGL seems pretty open.