Sega's producer on the game, Omar Woodley, describes one of the challenges as "gangsta style." See, when you kill 50 zombies while pointing the Wiimote sideways, like a "gangsta," then it unlocks a certain feature. Sadly, Omar wasn't willing to give it up on the feature, but the prospect of other unique challenges such as this does sound fun. Plus, there's the whole killing lots of zombies part of it.
Who else can't wait until February?