Excellent writeup. It really helps when the conversation is steered away from terms like 'amendment', 'advertisers', 'enforcement', 'criminality' and steered back to the central idea of recovering and safeguarding an intuitive and traditional idea of privacy in personal communication (postcard analogy). Lots of people, many with vested interests, insist that this isn't possible, that the genie is out of the bottle. But let's at least try, right?
In fact, PGP was a neat solution for the internet of the '90s with its quaint directory services (Bigfoot, anyone?) and dialup links. I think it had Pretty Good uptake too. So I'm very interested to see what can be done in today's environment.
(Your exchange with jmillikin looked promising too. Did it continue?)