That’s super nifty, John, some really good extensions of the idea. There can be concerns on using this in a course context since if the post to email address gets in the wrong hands, it can be abused.
The way JetPack PostByEmail works (its been more than a year since confirming) to make an account that uses it put things in draft rather than post, the user role needs to be Contributor. but this means no media in posts. So there is no way to moderate (if that is needed, obviously in a person photoblog, not a prob)
I got around this for one project by creating a gmail account that was the “public” address for submitting, and we would let it handle spam patrol, and then we had someone review in GMail, then forward to the Post By Email address.
In my SPLOTs, I prefer to set up a domain email address that forwards to the post.wordpress.com one, so I can easily change the forwarding one w/o revealing the actual one.