My main reason for asking this question is that I hit a snag in my current projet where glGenTextures returns a 0 in for the texture id, which doesn't seem to be valid. It appears to do this after it has already loaded a number of textures (about 5-6). I couldn't see the problem so I begain looking into the glCopy option.

My current texture class can load from file or tstream, it used SDL_Image and SDL_RWops to accomplish this. If you're interested I'll post the code for you to look at