Say you have an ASP.NET MVC project and are using a service layer, such as in this contact manager tutorial on the asp.net site: http://www.asp.net/mvc/tutorials/iteration-4-make-the-application-loosely-coupled-cs

If you have viewmodels for your views, is the service layer the appropriate place to provide each viewmodel? For instance, in the service layer code sample there is a method

    public IEnumerable<Contact> ListContacts()
    {
        return _repository.ListContacts();
    }

If instead you wanted a IEnumerable, should it go in the service layer, or is there somewhere else that is the "correct" place?

Perhaps more appropriately, if you have a separate viewmodel for each view associated with ContactController, should ContactManagerService have a separate method to return each viewmodel?