New (or old) Mocking Syntax?

Is it possible to do the following, or do I have to use a Mocking framework? And if I do use a mocking framework, do I have to do anything special?

private IClassificationService fakeClassificationService = delegate {
    System.Net.ICredentials Credentials
    {
        get { return null; }
        set {}
    }

    IList ListAllProjects()
    {
        return null;
    }
}

Edit: Looks like the new Rhino Mocks comes close to what I’m looking for