Author of the Learn Cocos2D book series published by Apress. The latest edition "Learn cocos2d 2" uses cocos2d 2.0 with ARC enabled and also covers Kobold2D.

Steffen is the developer of Kobold2D (free) and KoboldTouch (commercial), both game engines build on cocos2d-iphone. KoboldTouch adds MVC and component support and even improves cocos2d's own features, such as Tilemap rendering.

Learn more about Koboldtouch here.

Steffen's main website is Learn Cocos2D.