While I agree with the need to think before posting, I disagree with the above comment. I frequent many forums where there is no time limit on editing comments, and this simply isn’t a problem. If substantial new information is added to my posts here within the time frame I can edit posts, I usually clarify by prefacing it with “EDIT:” and the new content. The beauty of forums is that they become a community, and communities are pretty good at self-policing. I can almost guarantee you that if someone were to edit their posts to cause confusion that someone would comment and discourage the behavior. A top-down solution simply isn’t necessary here.