Disclaimer: I am one of the founders of SweetLabs (the company behind Pokki).
There are no revenue sharing requirements for the use of third-party ad services and third-party payment providers at this time (though the providers must be approved - list forthcoming). We're still very much focused on developer and user adoption right now.
That said we will be offering our own monetization options next year and there will be very favorable rev-share requirements tied to those for developers.
You are essentially giving up very little beyond time to participate in this contest!