And here are some replies to the "meta" part of that email exchange:
akkartik: "Thanks! I find myself wishing we could put Ross's long response in the 'namespace' section of the page rather than the 'meta' section."
I was conscious of that when I sent that reply. I'm not sure how to reply to a particular "subthread" when it's email. >_<
The only time I've ever seen email become a threaded tree is in mailing list archives, and I kinda assumed that had to do with automatic detection of quotations or something.
akkartik: "(I'm not actually expecting you to do this, just thinking aloud about how someone could maintain hygiene when managing a forum.)"
The difficulty here isn't managing one forum, but managing a conversation that spans multiple communication media. Unfortunately, I don't expect there to be a nice bridge that eliminates more complexity than it introduces. That kind of synergy tends to rely on foresight on the part of both systems.
Actually, email supports threaded trees using the References: header. Every message adds the ids of all messages it's under, and it turns out that is enough information to recreate the tree structure. Text-mode email clients like pine and mutt use this.
Given my history with those programs, I'm anal about hitting reply on the precise message in a thread that I'm replying to :) That helps list archives get the tree structure right even though it's invisible over gmail. So in your place I'd have split my message into parts and attached them to the right messages in the thread :) I know, it's utterly ridiculous and irrational.