some forums set the post edit time to 20 minutes, others to 1 hour. and some allow a longer period to allow the OP to make corrections.
its all about allowing the OP to post something. have a bunch of replies based on that post added. and then the OP changes their post to something else. and the people who replied now feel abused because their answers no longer match what they replied to.
there is a "report" button which i find useful for submitting requests to have a certain post updated, moved or deleted.
as for when a user asks to have their account and posts deleted; this can be handled several ways. personally, i grant their request, but keep their posts, and have them all marked as created by "unregistered." so the actual content is kept, and the conversation flow is not destroyed.
