Had this response from System 3 after sending them an e-mail via their contact form.
Hi Craig, Thanks for your email and sorry for the delay in replying. We are just finishing the X360 version of Putty at the moment. However, the game is being released via XBLA for X360 rather than as retail version. This decision was made a fair while ago and therefore I am not sure why Game would have taken a pre-order for this version. Unfortunately, it is not possible to release it this side of Christmas and therefore it will not be available until January. Sorry about this but hopefully it will be worth the wait. Regards John.
Hopefully they'll be true to their word. I've already cancelled the preorder with game.