I just turned on the pygame.OPENGL flag in my set_mode out of curiosity.  It made my code very unhappy: pygame.error: Cannot call on OPENGL Surfaces on the first screen.fill((0, 0, 0)).
I don't NEED OpenGL, but I'm kind of curious about it.  Where could I find info about pygame/SDL and OpenGL?
The OpenGL flag in Pygame is used to turn your window into an OpenGL projection for other libraries - such as Rabbyt or PyOpenGL - to use.
For sites on reading up on all of this, I would recommend starting out at the respective sites for PyGame, OpenGL, et al. I'd post links for them, but the spam protection mechanism requires for me to have some manner of reputation.
Where can I find information about what/why pygame can(not) do with openGl surfaces?