I am working on an ASP.Net MVC application that with views that I want to be able to format for desktop browsers as well as mobile browsers. Both formats would use the same Con
I would detect the browser in the controller and return the appropriate view. I guess you could override the view engine but that really seems like overkill to the extreme.
ScottHa has this post about targeting multiple devices with ASP.NET MVC addressing that same problem.
I would suggest either in the view or in something between the controller and the view (the ViewEngine...)
I'd go with custom attributes stuffing appropriate views/masterpages around the returned Model. We use this tactic heavily for Ajaxification, shouldn't be difficult to extend the concept to mobile.