In their press conference earlier, Nintendo didn't reveal everything. In fact, after the show, they announced a raft of software, all presumably less important than Just Dance 4. Among these was Wii U title, Game & Wario.
It's a new name for an old concept. Game & Wario is the successor to the WarioWare series, a collection of unique 'micro-games' traditionally used by Nintendo as proof-of-concept for new hardware and weird control schemes. Like it did with the Wii's motion controls and the DS' touchscreen, Game & Wario leverages the unique functionality of the Wii U controller.
A micro-game called Arrow transforms the WiiPad into a hi-tech bow used to defeat a bustling pack of enemies. Fruit allows one WiiPad-wielding player to anonymously control one of the other players on screen to quietly steal scattered fruit. Ski sees players lead a skier to the finish line by tilting the WiiPad. And Shutter uses the WiiPad's camera to take shots of hidden criminals.
Wario's party games are never the deepest or most complex experiences, but they're perfect at showing off whatever bright ideas are rolling around Nintendo's head.