After numerous rounds of "We don't even know if Osama is still alive", Osama himself decided to send George Bush a letter in his own handwriting to let him know he was still in the game.
Bush opened the letter and it appeared to contain a single line of coded message: 370H-SSV-0773H. Bush was baffled, so he e-mailed it to Condoleeza Rice. Condi and her aides hadn't a clue either, so they sent it to the FBI. No one could solve it at the FBI so it went to the CIA, then to NASA.
Eventually they asked Britain's MI-6 for help. Within a minute MI-6 cabled the White House with this reply: "Tell the President he's holding the message upside down."