Hi,
PubNub is a messaging system agnostic to the platform ( read, it's not just for IOS or mobile, it's reaching almost every possible app or software you can think of).
I am not aware of any support for PlayMaker at the present time. Currently, I would recommand using Photon and RPC calls, as this is indeed what pubnub is about, simply connecting apps and sending messages, something that pun does very well as well.
Typically, if you look at the chat implementation int he photon playmaker example, you'll get exactly what Pubnub can deliver ( also pubnub will have different ways to connect apps together, essentially it's same).
so, think of push notifications as "chat" and you have the base for it.
Bye,
Jean