Forumites on the Penny Arcade thread for SSBB spotted clear evidence of previously unconfirmed characters hidden inside the official video linked above. At 4:21 there are some frames that show a couple stickers selected. At the bottom right of the screen the game displays little icons for the playable characters the sticker buffs in the one player game.


This is where we find some familiar likenesses including highly suspected brawlers including the returning Jigglypuff and Ness(!) and newcomer Lucario!!! Okay so I barely know who Lucario is other than he's one of the Pokemon that can say more than his name in Pokemon movies. But hey, way to go Penny Arcade forum people!
UPDATE: Wow, this completely confirms Nintendo slipped up: they've edited the video! Now the sections of the screen that showed the stats for the stickers are totally blank! Way to totally confirm things Nintendo!