I guess it'll look something like the 3DS home screen on the controller, with your games and app icons.
But the TV will show the Miiverse thing, with big floating icons and your friends gathering round chatting about it.
It's like Twitter (trending) but just for your games, and with actual real world use. Can't wait to use this thing!!
Sounds amazingly ambitious, unique and a wonderfully fun idea - well done Nintendo!