From Nintendo's US Media Summit just now, thanks to IGN:
One more piece of news: Mario Super Sluggers. Coming to America. "We think that this is going to take these three wonderful areas of Mario, baseball and the unique capabilities of the Wii remote and bring them together in an exciting experience."
NOA's Bill Trinen takes the stage to chat about Mario Super Sluggers. Begins demoing the game. Previews the pitching and hitting mechanics, which are operated by the Wii remote. Gamers will pitch the ball by making a throwing motion with the Wii remote. To add spin to the ball, players simply twist the Wii remote while throwing.
Fielding the ball seems extremely simple. Bill just shakes the Wii remote and the fielders will automatically run toward hit balls. Once a ball is scooped up, he makes a throwing motion and they auto-throw it to the intended base.
Several of Bill's movements have gone unrecognized by the game. Not a very good sign.
Now Bill demonstrates the batting mechanics. When the ball is pitched, he can pull back the Wii remote and make a swinging motion to hit it. Alternatively, he can make a quick jerking movement with the Wii remote to hit the ball -- ideal for players uninterested in making grand movements to play Wii titles.
"Very simple and very approachable. It's based entirely off motion control. It's going to take the Wii Sports crowd and bring them into something that's more of a robust experience," Bill explains.
From seeing the demo in motion, we can confirm the following characters thus far: Mario, Luigi, Princess Peach, Daisy, Bowser, DK, Hammer Bro, Baby Mario, Baby Luigi, Waluigi, Wario, Toad, Toadette, Shy Guy, and Boo. The two teams in play were the Mario Fire Bats, and the Peach Royals.