Is there a hack to put a time limit on user post editing?

Basically to say a user can only edit their post for x days (hours/minutes whatever) after the initial post. To keep people from going back and editing a post that is several months old.

There isn't, but one could be made.

Simple time comparing will do the trick, such as:

Admin sets time limit in control panel (written to some vars file),
then when user clicks the "Edit" link, it'll (along with some other checks already existing) see how long since the post was made, and if it exceeds the time written to the vars file (set by the admin), don't allow the user to edit his post.

Uhm, sorry for a bit wordy reply... but you get the drift.