Selecting and Dragging an Item from "Yesterday" to "Today" on the Agenda Pane reschedules an item from "Yesterday" to "Today".

(For new users perhaps add an "Are You Sure?" message prompt, on the first use, before it saves the change, just to warn folks who didn't expect it. But include a "Don't show again" checkbox so the repeated warning doesn't annoy users once they get used to it.)