The facility to modify posts has been removed from Ensign First Class Blather, it is difficult to have a proper argument if someone is editing a post that your a replying to. The message informing you that additional posts have been made since you starting typing are invaluable, however, they are utterly useless if people simply add their new thoughts to the bottom of their previous posts.
The removal is an absolute bastard if you've made a typo, though.