To be clear, I've not gone into the realm of punishment, I just feel incredibly frustrated and sometimes it seems like there is nothing else! However, as so many of you have suggested, one thing I havent done is get him to clean up his own mess. I've always had him go get clean undies and clothes, but DH and I have always cleaned up. Great idea - I'll start him on that for the next accident.
I understand your frustration.. But my sanity saver is knowing that it really does just click.. He is my 2nd child, so I have seen it just click before.. And you don't tend to believe it happens, no matter how many times people tell you, until you have seen it for yourself.. Hang in there