The Opera Company of Philadelphia was instrumental in bringing it together to perform one of the Knight Foundation's "1000 Random Acts of Culture" which they'll be doing over the next three years across the country. Accompanied by the Wanamaker Organ - the world's largest pipe organ - the singers burst into song at exactly noon.
I got this embedded video from the Creative Minority Report blog.
Wouldn't you just love to have been there?!! Sent chills up my spine!!