I am inclined to decline this. Despite Jacmoe's emphatic support, I still believe that we should stick to standard compliance.
Replace double underscores with single underscores is Ok. But you never know what port of Ogre may not support #pragma once, which is why I am apprehensive.
Good work, transporter!
Just want to mention that in the odd case that it will break for some obscure compiler, there is the option of processing the framework..
I know.. And I am inclined to respect the decisions of the Ogre team. :)