Yoshi's Land for Wii U appears to have been outed by Canadian retailers Best Buy and Future Shop, with both stores listing the game for a December 31 release.
"Take Yoshi on an epic adventure to remember in Yoshi Land for Nintendo Wii U," says the description. "Check out Yoshi as you've never seen him before: in glorious high definition. Enjoy dual-screen control thanks to the Wii U Touchscreen GamePad, while you'll also be able to experience full integration with Nintendo's MiiVerse service."
Interestingly Yoshi's Land for Wii U has not been officially announced, so whether it'll arrive as soon as December 31 remains to be seen. It doesn't seem likely, although a future release (perhaps next year) is more than likely.