The SDL_OPENGLBLIT code should now work on Win32 with the latest CVS snapshot:
http://www.libsdl.org/cvs.html
In addition, the cross-compile headers now include glu.h:
http://www.libsdl.org/Xmingw32/opengl-cross.tar.gz
The SDL_OPENGLBLIT code may work on BeOS and MacOS, but it hasn’t been tested.
Enjoy!
-Sam Lantinga, Lead Programmer, Loki Entertainment Software