With Xcode 6, StoryBoards have also been added for OSX Apps. But when I create a new application in Cocoa, the storyboard button is disabled.
Did I miss something?
Storyboards are a feature of OS X 10.10 (Yosemite). If you run Xcode 6 on 10.9 (Mavericks), you will not be able to use them.