Out parameters and exceptions

Question

Say I have the following code:

    static void Fjuk(out string str)
    {
        str = "fjuk!";
        throw new Exception();
    }

    static void Main(string[] args)
    {
        string s = null;
        try
        {
            Fjuk(out s);
        }
        catch (Exception)
        {
            Console.WriteLine(s ?? "");
        }
    }

When I test it, s has been initialized to "fjuk!" when it's used in the catch block.
Is this guaranteed by specification or is it implementation dependent? (I have searched the C# 3 spec but couldn't find out myself)