I had a quick look on Airplay (Marmolade?) CIwUITextInput - which is keyboard event handler.
From what I remember the problem was, that this handler needs two Airplay engines: IwUI and IwGx. IwGx is Airplay rendering engine - sort of OpenGL competitor. Cocos2d uses OpenGL - and from what I read it should be possible to run both simultaneously. In my quick test, it fell into pieces. Also starting another rendering engine just to implement key handling on limited resources devices - not cool
(can you move this topic to Airplay forum? sorry, my mistake)