Neither 10k+ users nor ♦ moderators can read deleted comments, so a deleted comment is as good as gone.  The comments, do, however, [still exist in the database](http://meta.stackoverflow.com/questions/26813/please-improve-the-history-audit-trail-of-moderator-actions-for-moderators/26819#26819) and Jeff can see who deleted them should there be an issue.