In case you haven't noticed the blog and aren't on the Kickstarter mailing list, please note that the export format has changed. See here for more information:
http://esotericsoftware.com/spine/cocos ... at-change/
Also note we are changing the default project file extension from ".project" to ".spine". The file extension is just a visual thing of course, you can name your files whatever you want, but we are doing this so we can have file associations start Spine.
There is one small piece of functionality this loses. Previously you could export an animation from skeleton A and import it to skeleton B. This would actually work if the skeletons had bones with the same hierarchy and names. You now import a whole new skeleton, you can't just import an animation to an existing skeleton. If we want to support moving an animation from one skeleton to another, we can add proper drag and drop support in the tree for doing this.