ok i think i might know the thing behind the classic controller

http://a308.ac-images.myspacecdn.com/images01/34/l_3eb008eec87c7ff6e3327de7671ac2c3.jpg

now i will most likey be wrong but i think it might have to do with some kind of rumble slot.

Clearly something can be attached to the back of the Classic controller. More than likely it will be hand grips or something. 

Clearly something can be attached to the back of the Classic controller. More than likely it will be hand grips or something.

jedibron

did i say  i knew it people know i said i will most likey be wrong.

 though there is something for it.

i think the wii remote is going to attach to it.  Why?  remember when nintendo said that super smash bros brawl was not going to use the wiimote and nunchaku.  well, why not have an attachment for the classic controller where you could aim an item at an opponent for massive damage.

That's my theory behind it.