Most of the answers I see that discuss what the model layer is comprised of, only address stateless MVC, particularly ASP.NET's implementation of it. When working with desktop MVC frameworks such as Cocoa, is application state considered as part of the "Model" layer?
Yes, the Model is where state visible to the user is traditionally stored. As others have stated, there are different types of state: a view state for example, affects only the view, and would not be part of the Model. Even in a "stateless" MVC, there is going to be some persistent state somewhere, and that is considered part of the Model, even if the Model is thrown out and reconstituted on each request.