I use past-dating to post things that happened on paper/etc to the day when they actually happened. I have a slow-going project to put my paper journals in here so they're all in one place. 2b2 would break the hell out of that. ... oh, right, recent page only, rather than the archives.

In the event of something more than, say, 48 hours off server time, I propose something like an inbox notification, in a classification by itself so people can go through and make it vanish in one fell swoop if it bothers them: a notification that on [server timestamp], their entry [title and link] was posted with a [manual timestamp] -- in case it goes very odd and they're not sure where it went.