I wrote a C++ wrapper of Chartboost for Cocos2d-X recently. Currently supports Android and iOS.
Chartboost is a platform for internal cross-promotion, direct cross-promotion with other apps, or promoting across a wide network.(http://chartboost.com/web)
If you guys want to use Chartboost in your Cocos2d-X game, you can use this Wrapper easily.
repo address: https://github.com/wenbin1989/Charboost-x