President Bush recently called the pope, "Sir," instead of "Your Holiness," drawing gasps from the Catholics present. Personally, I cannot imagine a legitimate reason for Bush meeting with the pope in the first place (one reason my kudos is mixed), but if he is going to do so, he is at least to be commended for not referring to the pope by a misleading title. Nevertheless, I suspect that the use of "sir," was probably not calculated by Bush, but was an accidental reflection of his Protestant view that the pope is not an especially holy person. I'm confident that most official correspondence from Bush to the pope would use the misdescriptive title that the journalists in the story (linked here) were so shocked not to hear.
But, if it was intentional, then Hat's Off to You, Mr. President!