By the way, this is a great solution to the much-discussed (http://news.ycombinator.com/item?id=2774254) problem of effectively dealing with plagiarism: imagine if it were expected, as part of your class, that you engaged your professor via email while writing assignments. There would be no way to plagiarize, because the professor would have direct insight into each part of your writing process as he saw bits of your essay fall into place. Imagine all the students that could be guided to correctly cite and re-use sources if their professor had just headed it off at the pass instead of running it through TurnItIn and groaning at the fallout. I couldn't agree more with the benefits of this dynamic, more interactive teaching method for writing.
It also makes me wonder if he would be interested in having students share their works-in-progress via Google Docs--he would be able to essentially peer over their shoulder as they type and comment. Or would that be going too far?