I wrote up an article a while back on a few different options for coordinating between views: http://lostechies.com/derickbailey/2011/07/19/references-routing-and-the-event-aggregator-coordinating-views-in-backbone-js/
in your case, i’d recommend using the event aggregator that i describe in that article. you could have each item view listen for a “editmode” event, or something similar. when this event fires, each view that listened for it would update itself to go into edit mode. then you would do the opposite when you click “done” – send a “viewmode” event, or something similar, and have each view update itself appropriately.