[RAILS 3] 2 sup app in 1 app


I'm building an app which will become quite big (I hope :wink: ) and so I
want to separate admin part and customers part. By separate, I mean not
2 namespaces (=1 app), but really 2 app (so I can shutdown customers and
keep admin access for example).
But, because the logic/model is the same, and some conf too, I would
like to keep it in one directory (a rails 3 app folder).
In rails 3, the app is a rack app, we have :