I know this feature has been requested in the past but I wasn't sure if commenting on a old post would bump it or not.
Having the ability to allow the schedule of publishing or retiring of apps allows for so much flexibility. If someone has forms that are used 24/7 and a change needs to take effect at midnight on a set date, scheduling allows them to have it go live with no issues. Right now, the work around is to duplicate the app and instruct users to use one after the set time, then retire the old one later. Or have someone sign on at midnight to publish/retire but who wants to do that? :)