Media Bistro's "AgencySpy" blog explains "why it's vitally important to watch what you say on Twitter":

A representative from Ketchum New York (a PR and Marketing firm) heads to Memphis to give a big presentation to their big client, FedEx, and totally offends everyone who works there before even stepping foot in the building.

Upon landing in Memphis and getting a lay of the land he tweets:

"True confession but I'm in one of those towns where I scratch my head and say, 'I would die if I had to live here.'"

Someone from inside FedEx was following Capt. Footinmouth, whose Twitter name is 'keyinfluencer' -- quite possibly the douchiest nickname of all history -- and that person sent the letter we posted below. You'll want to read it, because not only is it amazingly poignant, but because it was copied to "the FedEx Coporate Vice President, Vice President, Directors and all management of FedEx's communication department AND the chain of command at Ketchum." Thank you Peter Shankman for sharing this story.

"Mr. Andrews,

If I interpret your post correctly, these are your comments about Memphis a few hours after arriving in the global headquarters city of one of your key and lucrative clients, and the home of arguably one of the most important entrepreneurs in the history of business, FedEx founder Fred Smith.

Many of my peers and I feel this is inappropriate. We do not know the total millions of dollars FedEx Corporation pays Ketchum annually for the valuable and important work your company does for us around the globe. We are confident however, it is enough to expect a greater level of respect and awareness from someone in your position as a vice president at a major global player in your industry. A hazard of social networking is people will read what you write."

(Main story originally found, naturally enough, here.)

Related: Via Melissa Clouthier, helpful new media definitions--like, um "Twitter!"--are defined definitively, here.