A New Super Mario Bros. Wii arcade cabinet has launched in Japan, and it's developed by Capcom not Nintendo.
According to Siliconera, New Super Mario Bros. Wii Coin World is a four player game in which you earn medals by participating in a variety of different mini-games. Running and jumping doesn't seem to figure too prominently.
Yes, our April Fools' alarm started ringing too - but this one appears to be for real. The game has a full product page on Capcom's Japanese site and there's a trailer too, which you can check out below.
Nothing has been said about a European release but given the health of the arcade scene on these shores we wouldn't hold your breath.