ShopTo.net have recently announced a Gears Of War 3 SteelBook:
http://www.shopto.net/XBOX%20360/VID...20Edition.html
It is due to be released on the 20th of September 2011, and retailing at only £42.85!
Not sure if it's exclusive or not, but seems that way at the moment
This is also the fourth UK edition to surface for this game. The other three being the standard edition, the "Day One" Limited Edition, and the Epic Edition!