The time limit is supposed to be 6 hours for all forums except the mods forums (where mod creators are allowed to edit their posts for a much longer period of time). If you were able to edit a post in any other forum, then it's a result of the forum crash over the weekend. As soon as I can find time, I will go in and check all of the settings.

Edit: I've moved this portion of the discussion out of the Island Events thread to keep things on track.