reaver894: There is no agreement between steam and gog for this type of thing, there isnt really anything in it for either company (the exception might be The Witcher games, cant remember)
Anyway, as im sure you know GOG are a drm free distributor, you can back the game up and basically do whatever you want with it within reason(no reselling or distributing and such)
You cannot and I doubt you ever will be able to get a code to activate on steam, you can however add the game to your steam library using the add non steam game. But any updates will not come through your steam client.
Im more than a little drunk at the moment so if someone wants to correct me feel free and while your at it my car needs a clean you damn busybody