Was down at the local Gamestop/EBGames/Almost Ultimate Game Sales Conglomerate of Doom and lo and behold, Super Mario Galaxy is playable on the Wii! My guess is they have the complete version running, so be sure to check it out! You may want to reset the game though as when I picked it up, there was just a HUGE block of text to get past that took maybe five minutes of just pressing 'next, yes sure I was listening to what this person I didn't understand and don't care much about had to say'. So I can't comment much, unfortunately!
But it's playable, so go check it out!