Siliconera breaks down the 12-person gameplay of WarioWare: Smooth Moves on the Wii, including a video of the various games. The main multiplayer matchup requires players to pass a controller between the up-to-12 players when it's the next person's turn. (That seems to make more sense than trying to divide four controllers.)
The video shows the process in action, with quick glimpses into hula-hooping, whack-a-mole, grabbing fish, and many other mini-games. WarioWare could be a fun party game, but we're holding our applause until we try the game at home; we can't always predict which games will keep our gamer and non-gamer friends engaged.