Preordered, got the key pretty much the same time as the preload on Steam started so I could join in the fun. It might vary but yeah.
Batman AC is another matter I think since it isn't Steamworks. I think it uses Capsule (which I haven't used yet). Someone pointed out you don't (or can't) make a backup in this case; not entirely sure but probably because you can trade it back in. Again, no idea how Capsule works or if you can even touch the install directory.
Actually, I'm not so sure but can you even trade-in/resell a GFWL title? I thought you had to link the game's CDKey with your GFWL/XBL account.