I've searched for information on this, but cannot find it, is this not something you can do yet with Kobold2D/Cocos2D? or are there options I've missed?
You can make your game using the Cocos2d framework and GameKit framework combined, there should not be any issue with that.
What you need to do is create the user interface using Cocos2d framework and then handle the turn based events using the classes provided by game kit framework.
If you are creating a card game (like uno) in Cocos2d, then you will be using the