In this question I learned that you have to download patches for games on the Wii/3DS manually from the Nintendo store.
I can't think of why some games, like Legend of Zelda: Twilight Princess or Super Paper Mario would have patches, and my experience with game updates on the PS3 is that you are notified automatically about the update when you play the game (a bit too often if you ignore it).
While I have no problem having to manually download a patch from the store I wonder if the Wii or 3DS will notify you if a patch is available or not since I will rarely go into the store and a patch may not actually exists when the game is initially released (I tend to only enter the store to check on DLC)