Obfuscated CLR/C# 2.0

// Obfuscated CLR/C# 2.0 programming challenge.  Predict the output of this program without
// using any compiler to build & run the code.  Explain your answer.
//
// Mike Woodring
// http://www.bearcanyon.com
// Bear Canyon Consulting LLC
//
using System;
using IAR = System.IAsyncResult;
using IE1 = System.Collections.IEnumerable;
using IE2 = System.Collections.IEnumerator;
using MRE = System.Threading.ManualResetEvent;
using PTS = System.Threading.ParameterizedThreadStart;

class P
{
    static void Main()
    {
        MRE fe = new MRE(false);
        MRE pe = fe;
        foreach( char c in new MSG() )
        {
            MRE ce = new MRE(false);
            PTS m = delegate(object s) { P p = (P)s; p.W.WaitOne(); Console.Write(p.C); p.G.Set(); };
            m.BeginInvoke(new P(c, pe, ce), delegate(IAR ar) { ((PTS)ar.AsyncState).EndInvoke(ar); }, m);
            pe = ce;
        }
        fe.Set();
        pe.WaitOne();
        Console.WriteLine();
    }

    public P(char c, MRE w, MRE g) { C = c; W = w; G = g; }

    char C;
    MRE W;
    MRE G;

    class MSG : IE1
    {
        public IE2 GetEnumerator()
        {
            int i = 0;
            foreach (char ch in new NTE<SM.B>()) yield return (i++ == 0 ? char.ToUpper(ch) : ch);
            yield return (',');
            yield return (' ');
            foreach (char ch in new NTE<SM.A>()) yield return (ch);
            yield return ('!');
        }
    }

    class NTE<PT> : IE1
    {
        public IE2 GetEnumerator()
        {
            foreach (Type t in typeof(PT).GetNestedTypes()) { yield return t.Name[t.Name.Length - 1]; }
        }
    }

    class SM
    {
        internal struct A
        {
            public struct cow { }
            public class too { }
            public interface car { }
            public enum will { }
            public struct pad { }
        }

        internal class B
        {
            public class wish { }
            public struct see { }
            public interface hill { }
            public enum ball { }
            public class boo { }
        }
    }
}