In all seriousness, though, how this began is a really nice story. According to the NORAD site, "For more than 50 years, NORAD and its predecessor, the Continental Air Defense Command (CONAD), have tracked Santa's flight. The tradition began in 1955 after a Colorado Springs-based Sears Roebuck & Co. advertisement for children to call Santa misprinted the telephone number. Instead of reaching Santa, the phone number put kids through to the CONAD Commander-in-Chief’s operations "hotline." The Director of Operations at the time, Colonel Harry Shoup, had his staff check the radar for indications of Santa making his way south from the North Pole. Children who called were given updates on his location, and a tradition was born. In 1958, the governments of Canada and the United States created a bi-national air defense command for North America called the North American Aerospace Defense Command, also known as NORAD, which then took on the tradition of tracking Santa."
Our hats off to the folks at NORAD, who take their work seriously, but apparently aren't above having some fun for the kids.