Inherited interface property not found by Model Binding in MVC3 but works fine in MVC2

UPDATE: Problem Solved.

Darin Dimitrov's answer contains a link to another, related question. One of the proposed solutions on that page ended up working for us.

Original Question

The code sample below works in MVC 2 but throws an exception in MVC 3. Does anyone know why MVC 3 introduced this breaking change? Is there a way to get this working in MVC 3 while still allowing me to describe the viewmodel as an Interface from within the view?

There is another related question on StackOverflow, but it doesn't give me any info as to why there is a difference between MVC 2 and MVC 3.

Model

public interface IPerson {
    string Name { get; set; }
}

public interface ISpy : IPerson {
    string CodeName { get; set; }
}

public class Spy : ISpy {
    public string Name { get; set; }
    public string CodeName { get; set; }
}

Controller Action

public ActionResult Index() {
    var model = new Spy { Name = "James Bond", CodeName = "007" };
    return View(model);
}

MVC2 View (Works perfectly)

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<MvcApp.Models.ISpy>" %>
<p>CodeName: <%: Html.TextBoxFor(x => x.CodeName) %></p>
<p>Name: <%: Html.TextBoxFor(x => x.Name) %></p>

MVC3 View (Throws exception)

@model MvcApp.Models.ISpy
<p>Name: @Html.TextBoxFor(x => x.Name)</p>
<p>CodeName: @Html.TextBoxFor(x => x.CodeName)</p>

MVC3 Exception Information

I am showing the relevant exception info below, but you can view the ent