Given that it's an action normally reserved for useless comments or threads, whilst not being as extreme as delete, shouldn't it have a Yellow scrollover? Right now it's just the normal gray.
I love the look of the Preview now, much better than the old yellow box! I'd think about adding an edit icon instead of the current "Keep editing" and the current Tipsy notification. Or maybe just clicking on the post to edit it. The current implementation seems overly complicated.