I think it'd be cool to be able to specify a post you are posting as "Community editable". Meaning anyone (who's a registered user) can edit the post in the same way one edits a wiki. It wouldn't apply to that entire thread, just the one post. This way, users can collaboratively edit a cool snippet of code to incrementally improve it.
The post could visually have a different colored headerbar, and say "Community editable" at the top. Seeing that posts already have histories, I think it could work very well.