I had to update a comment earlier today and thought the exact same, not that it was popular or had any comments. This feature could also be used to discredit another user. For example, Person 1 posted a critical argument about the tea party movement. Person 2 responds Yeah I totally agree. Their actions have proven that they are only interested in protecting their financial interests. There will never be peace and true equality while they continue to influence American politics. Person 1 then changes their original comment to I hate [insert persecuted race]. An extreme example, which I am sure would never happen. I guess any further comments could easily be removed or edited by their authors to reflect the change. A feature could be added to identify when a comment has been added once it has already been commented on.