Can One execute your body of the virtual method that endures an abstract class that has been mocked using Rhino Mocks?

To become obvious, I am not attempting to mock the behaviour from the virtual method. I am attempting to /test/ the virtual method (around the mocked class).

Is idea a blatant misuse of Rhino Mocks?

Yes, that needs to be absolutely fine. I can not say I have attempted it, but I'd be very surprised whether it unsuccessful.

EDIT: I suspect you would like the PartialMock method. Here's a good example:

using System;
using Rhino.Mocks;

public abstract class Abstract
{
    public virtual int Foo()
    {
        return Bar() * 2;
    }

    public abstract int Bar();        
}

class Test
{
    static void Main(string[] args)
    {
        MockRepository repository = new MockRepository();
        Abstract mock = repository.PartialMock<Abstract>();

        using (repository.Record())
        {
            Expect.Call(mock.Bar()).Return(5);
        }

        Console.WriteLine(mock.Foo()); // Prints 10
    }
}

EDIT: Or perhaps in my first attempt for AAA:

using System;
using Rhino.Mocks;

public abstract class Abstract
{
    public virtual int Foo()
    {
        return Bar() * 2;
    }

    public abstract int Bar();        
}

class Test
{
    static void Main(string[] args)
    {
        // Arrange
        Abstract mock = MockRepository.GeneratePartialMock<Abstract>();
        mock.Stub(action => action.Bar()).Return(5);

        // Act
        int result = mock.Foo();

        // Assert
        mock.AssertWasCalled(x => x.Bar());
        // And assert that result is 10...
    }
}

You have to tell Rhino.Mocks to call to the initial implementation rather than doing its default behavior of just intercepting the phone call:

var mock = MockRepository.GenerateMock<YourClass>();
mock.Setup(m => m.Foo()).CallOriginalMethod(OriginalCallOptions.NoExpectation);

You can now call the Foo() method in your mock object.