How does the nginx fit in? Do you install an instance of nginx onto every single box? Or can you elect to use a web server box as your frontend nginx and proxy request back to a set of separate servers running instances of passenger?
At the moment nginx sits on every frontend box serving Passenger. Unicorn support is coming soon. Split of front end proxy and backend server is further down the line. Feel free to put it down in the Feedback panel on the site and vote it up! Thanks.