Supergiant are apparently fully aware that when talking about Bastion over the summer, they say they designed the original game to be complete, and therefore not really requiring of DLC. Needless to say, that stance has changed a little, as they explain: "HOWEVER! In the weeks following the release of the game, we decided to put a little something together for the holidays as a show of thanks to our fans. So, on December 14, we’ll be pleased to bring you the Stranger’s Dream DLC for Bastion, which should give you some good reasons to come back to the game while preserving the core experience just as we intended." The Stranger's Dream will be "a new fully narrated Who Knows Where sequence, bigger and more challenging than the others", and there are two other new game modes, too.
The Stranger's Dream is out Dec 14th. It'll be free, too.