Three new playable characters have just been announced at the official website:
I'm not sure what kind of attacks Pac-Man will even have (though from watching the official video for him, it appears he'll have a bunch of oldschool game graphics attacks, sort of like Mr. Game & Watch), nor do I have any clue what Mii Fighters will do, but Palutena is AWESOME! Previously, she was Pit's final-smash attack, but now is a playable character in her own right. Makes you wonder what Pit's final-smash will be in SSB4.
Check out this official Nintendo-released anime video used to introduce her as a character in SSB4.