Yes, there seems to be more and more about email these days, but it seems like everyone is just putting a different interface on something that is not working as they want. I created a little mock-up of what I want out of email - just my 2 cents.
You click on a "subject line" in your gmail table view, and it opens up a to-do list, or a wiki, or a spreadsheet, or a regular old email.
Not an email "notification" that links me to a spreadsheet, but the actual spreadsheet itself.
I originally thought this was what Google Wave intended to be. You could send a regular email OR a "wave" and both would appear in your gmail inbox. It unfortunately ended up being more of a second inbox, with gmail notifications.