The e-mail client has the concept of panes, where you can get, say, a larger view of your entire message, without the list of messages, or of the inbox. You can just move things around. This is similar, it seems, to the fragments that Google showed for Honeycomb. This demo had a little glitch and the full HTML e-mail wasn't rendering.
With e-mail, you can create "cards" for each e-mail. That's a very nice way to manage through important e-mails. Sort of like multi-tasking e-mail.