Thanks Peter. I've posted some code below but from what I understand I will
return immediately and the thread will not be blocked. What does this mean
for event notification though, I assume that I will not be thread safe
because the OnProcessStateChanged handler below will be executed on a
available worker thread rather than the main thread?

public enum ProcessState { started, stopped, notstarted }
   internal delegate void OnProcessStateChangedHandler(ProcessWrapper
processWrapper, ProcessState oldState, ProcessState state);

public class ProcessWrapper
{
  public Process _process;
  public ProcessState _processState;
  public event OnProcessStateChangedHandler OnProcessStateChanged;

  public ProcessWrapper()
  {
      _processState = ProcessState.notStarted;
   }

  public void Start()
  {
      _process = Process.Start("notepad.exe");
      _process.EnableRaisingEvents = true;
      _process.Exited += new EventHandler(_process_Exited);
      _processState = ProcessState.started;

       if (OnProcessStateChanged != null)
           {
               OnProcessStateChanged(this, ProcessState.notstarted,
ProcessState.started);
           }
   }

void _process_Exited(object sender, EventArgs e)
       {
           if (OnProcessStateChanged != null)
           {
               OnProcessStateChanged(this, ProcessState.started,
ProcessState.stopped);
           }
       }
}

static void Main(string[] args)
{
ProcessWrapper process = new ProcessWrapper();
ThreadPool.QueueUserWorkItem(new WaitCallback(StartProcess),process );

process.OnProcessStateChanged += new
OnProcessStateChangedHandler(process_OnProcessStateChanged);

}

private static void StartProcess(object state)
       {
         ProcessWrapper process = state as ProcessWrapper;
         process.Start();
       }

static void process_OnProcessStateChanged(ProcessEntry entry, ProcessState
oldState, ProcessState state)
       {
         //Do something, is this thread safe?
       }