ID@Xbox the indie developer program for the Xbox One was originally announced this summer, promising independent developers access to development software and development kits just announced they are also including a free license to Unity. Unity being very popular middleware for start up studios, the partnership between Unity and Microsoft which was revealed in June seems to be paying off.
Unity also supports Windows phones/apps, IOS, android and blackberry so we maybe seeing more console ports of your favorite mobile games soon too. The licenses are going to become available some time in 2014, they are also going to support every feature the Xbox One has to offer including the Kinect and Smart Glass.
Microsoft are trying to remove a lot of the disadvantages some people face when starting up, they want to bring every developer to be equal, offering them the tools to create high quality games. Most people would not be able to afford the Unity license, they are targeting start up studios and developers, giving them access to resources larger companies have had for some time.