
Nintendo's UK website has issued a warning to its readers about the perils of mod chips, explaining what they do and why it's a Very Bad Thing.
The site goes on to say that installing a mod chip will render you sterile and kill your dog. Ok, it doesn't actually come right out and say that, but it's totally implied. To be fair, though, I don't think it's a bad thing for Wii owners, many of whom have likely never owned a game console before, to know the full mod chip deal, or else some guy at the game store who "knows everything" might end up convincing them that modding their Wii is the greatest idea ever, and then their Wii breaks, and then they're sad.
Information Regarding Mod Chips [Nintendo UK]