Since we are making progress to use secure mail transports, why are we not seeing more use of S/MIME to secure the contents of the message? I set up signing/encrypting on my mail clients, but have yet to see anyone, or any company, use it.
Inside an organization, Exchange will perfectly happily do secure mail - it works, it's nearly hassle free and novice users can do it.
Outside, you have a pile of Web of Trust problems which novice users don't understand, and no pushing requirement.
I am surprised that large businesses have tolerated this for so long. Maybe SMIME isn't the answer, but it's surprising that we haven't seen some method to guarantee secure delivery of mail between companies.