Sadly, itís not the Luigi DLC, nor is it Pro Controller support, but there is a new update for New Super Mario Brothers Wii U.
The incredible side-scroller has received a new update which sends Miiverse posts created in-game to a dedicated NSMBU community. This community was created specifically to prevent spoilers, but also to trade strategies, and create in-game discussion
The original NSMBU community remains, but will be more for art and general discussion.
The update should download automatically when NSMBU is downloaded from the Wii U menu.