It was announced on the Nintendo Direct live stream. Namco Bandai will be working in collaboration with Project Sora on the Super Smash Bros. games for the Wii U and 3DS. I'm guessing more will be revealed after the stream. Who's ready to play as Pac-Man?
Edit: Here's a message from Sora's Masahiro Sakurai and Namco Bandai's Masaya Kobayashi: Nintendo Direct Message