>Because its machine parseable, it makes a lot of presentation options available that aren't available when you rely on a standard hyperlink without a data format with a standardized identification of the requested action.

You're right: this addition turns email into a data or event queue of sorts with standardized actions that can be performed on it. I like it. Given that email is one of the few non vendor-locked communication technologies we have and we already have a lot of infrastructure to deliver it reliably, this seems a promising evolution path.

I'd like to see something similar for IM: currently SMS is the only open standard for instant messaging, and any other option locks you into either a platform or a specific client, which the other person will probably not use.