You can edit your post within 24 hours of the post being made. After that, no. We had issues in the past where people would go back and completely clear their posting history. It screws with the statistics of the forum and it looks, to put it bluntly, crap when there are loads of empty posts lying around. I'm not directing this at your specifically but if members just THINK BEFORE they POST, then there's no need to go back and edit past posts. Why is this such an issue? Genuine question, I don't get it. If I join a forum I don't make posts that I'm going to later regret... just think before you post... it's pretty simple.
Not to go off topic, but it was mentioned in a suggestions thread that you should be able to edit or delete your posts whenever. It's so much easier than contacting a mod, and will save them alot of time. Could this option please be considered?
edit - [MENTION=3171]v_melnik[/MENTION] what are your thoughts on this issue? I really don't want to allow members to edit their posts any time they like, but if the 24 time limit is a bit too strict then I'm willing to expand the time limit to a day more or so... What do you think?