Oh where or where is the IETF. This is the kind of thing that needs a standard for the message content in a way that is extensible. Maybe plain HTML/CSS is sufficient for most stuff. Does anything from the Jabber world work for this?

I hate the million inboxes I have. It would be nice if you could at least use one application to manage all the inboxes of all the devices.

Seems like Google Wave was a good first attempt at an open-source standard that could have worked here.