As of right now, there isn't a way to edit posts. We've all come to expect a typo here and there, and you can always reply to your message if you notice a typo.
The forums are (suppose to get) a little makeover, and editing posts has been tossed around before, I believe.
Whether it be for typos or to change an offending word or two, it is sometimes useful to be able to edit a post (as long as no one has posted a reply yet, which can cause discussion weirdness). Is there a way to edit posts here?