I don't understand. The iPhone Facebook app already has messaging built it, with notifications, so why a separate app?
I didn't read past the first page of the thread so maybe I missed something.
*edit*
I do have beluga because my GF can message me from the browser of her laptop without going to her phone. I know FB bought beluga, is this what they have done with it? In the pics for the app, there is a picture of a beluga whale as a nod to the app, and when you search beluga, the Facebook chat app is second result. But why a new separate app outside of beluga and not just Facebook integration?