Michael,
It's not that I'm opposed to changing WAI, but if I know the change you're referring to (changing ResponseEnumerator), it probably won't happen. ResponseEnumerator was designed the way it is specifically to allow things like proxy servers, where you don't know the status code or headers until you've initiated the response enumerator. I still think it will be possible to implement the API you're hoping for with the current WAI. Do you want to sketch out the initial work and then be in touch with me so we can develop it more fully?
It was Greg that asked me to implement a log system as a middleware. I think it's nice if we can implement such a middleware. But it's not my hope, it is Greg's hope. If people satisfy with the current wai-logger, it's enough to me. --Kazu