MS Hardware just announced a new Keyboard optimized for Windows 8 called Sculpt Comfort Keyboard. You can read more about the announcement at the Microsoft site. This keyboard apart from special keys to access Windows 8 features like Charms and Action bars also has a split Spacebar that has both Spacebar and backspace keys.
This keyboard is listed in the MS Store at $59.95 currently and so of today is marked "Coming Soon". MS Store also seems to have related Sculpt Touch Mouse that is also marked "Coming Soon" listed for $49.95.