CocoStudio has been started development since 1.5 year ago, it has only Chinese version at the beginning. We plan to release its English version in 1~2 weeks.
CocoStudio is an editors suite for cocos2d series engine. It has scene editor, GUI editor and animation editor, supports bone animation. Its output format JSON can be parsed by a new extension CocoStudioParser.
So far, CocoStudio has been written with .NET framework, so it can be only run on Windows.
For more details, you can read this wiki page [[CocoStudio]].