Ok, im gonna guess. A design tablet that recognizes the wiimote so it allows you to draw stuff (kinda like Mario Paint).

Image is only for demonstration purposes.
edit> its not likely that it is voice recognition, because Wii Speak already exists, and i dont know what else the DS does which is applicable for a Peripheral on Wii.
2ndedit> Ok, could it be related to Virgin medias appearance at the show? Mobile phone integration? (Nokia, hmm) Now im thinking about the potential of a 2nd screen too, which would be easily adaptable for a design tablet, or a mobile phone.
POSSIBILITIES!!!!!!
“When we make some new announcement and if there is no positive initial reaction from the market, I try to think of it as a good sign because that can be interpreted as people reacting to something groundbreaking. ...if the employees were always minding themselves to do whatever the market is requiring at any moment, and if they were always focusing on something we can sell right now for the short term, it would be very limiting. We are trying to think outside the box.” - Satoru Iwata - This is why corporate multinationals will never truly understand, or risk doing, what Nintendo does.







