Like I said, nrpy is a standalone daemon like nrpe is, and check_nrpy is a standalone "binary". It should be usable out of the box. About integrating it inside shinken, I don't know enough about the general infrastructure to answer that.
In fact for the client, the goal is to bypass a fork, and so give this nrpe lib to the "workers" (python process that really do the job) so they can just load it, launch the connexion without having to fork/Popen a process for it. I think we can expect huge performances for this :)
For the daemon, it can be a very good base for an enhanced agent. But it's far harder that just a "worker call" :p