Nintendo has signed a "long-term" license agreement to use the Unity Engine for in-house and third-party developers.
One is a long-running games company known for its lack of third-party support. The other is a popular game engine widely recognized by the indie gaming community. No one ever expected the two to join forces but now, as though they exist in some bizarre buddy cop movie, an unlikely partnership has formed between Nintendo and Unity Technologies to bring the indie-friendly Unity Engine to Wii U, presumably after both companies bust that drug kingpin and leap from an exploding helicopter. The license not only allows Nintendo to use Unity for first-party games, but also to distribute it among external developers, which might allow the Wii U to become a more open platform than its predecessor.
While details of the actual license agreement are still forthcoming, the fact that a license exists at all raises several intriguing possibilities. Nintendo hasn't always had the best relationship with third-party developers, something the company understandably doesn't want to repeat with the Wii U. The company already plans to open the system to third-party online networks, and the addition of Unity Engine support on top of that could draw back developers who found WiiWare restrictive as an indie platform.
Nintendo is currently in the process of optimizing Unity for the Wii U, with plans for an official release sometime in 2013. There's even the possibility that Nintendo's major franchises, including Super Mario or Kirby, might one day use the Unity Engine. We're unlikely to see any large-scale playable Unity projects for a few years, first-party or otherwise, but it's possible that popular games like Rochard could be quickly ported to the Wii U, allowing the system to quickly build up its games library with little effort on Nintendo's part.