Should we be allowed to edit comments?
How do I edit a comment that I left on a question?
You can't. You can delete a comment and then add a new one, though.
Just for the record, you CAN edit comments now (for a brief period after you submit it).
Add a new comment with your corrections in it, wait 30 seconds, delete the old one.
(It sure would be nice if the comment restrictions were lightened a little for users with a certain reputation threshold... but then, I dream of a world of ponies and rainbows and waffles too.)