I still maintain that blog comments should be left alone once published. The way WP has structured comments and editing capabilities is fine the way it is. There is nothing broken.
I know of one blogger who gets a lot of comments. Suppose a commenter goes to a particular post and deletes what he/she wrote. This blogger always responds to comments. What happens to his answer back? It hangs there and his response no longer makes sense. Who is he answering to? Also, there is a flow to his comments as the lines of communication evolve. By deleting (or editing) a comment here or there upsets that flow and balance and could alter the gist of everything stated. Should he then remove his own comments back to fill the void? Then, the commenter has control over the blogger.
Museditions may be on to something by opening the comment section with a disclaimer "to include a warning that all comments are public, and that the owner of the blog owns the content, and has the right to edit." That would clearly spell out policy. Also, an edit comment before publication area would be appreciated by potential commenters, as medteam brought up.