The new Super Smash Bros game is coming this summer--on Nintendo 3DS, at least. Game director Masahiro Sakurai confirmed that the 3DS version will be shipping first, coming this summer. The Wii U version will ship later this year, this winter.
Both versions of the game share the same roster, however there are different stages between the two. In addition, the 3DS version runs with an optional cartoon border meant to emphasize the characters when presented in 3D.
Sakurai also confirmed that most of the 3DS version will run at 60fps, while certain elements (like assist trophies) will render at 30fps. Both versions will also support online play, obviously.
The 3DS version will feature an exclusive mode called "Smash Run." It's a 4-player battle game set in a dungeon-like stage full of power-ups to collect. Players will be able to explore the stage and collect power-ups for five minutes, and then battle with enhanced fighters.
You can watch the entire 40 minute announcement video here: