Did you know that when a new pope is elected, that event is signalled to the faithful by the burning of the vote cards? The resulting white smoke which can be seen in St. Peter's Square is called the sfumata.  This is just one of the many interesting things about the Catholic Church I have learned by rereading the hyper-brilliant Endymion half of Dan Simmons' Hyperion Cantos.  I love these books.  I just started reading Rise of Endymion today.  I once wrote a paper on the Hyperion half of the Cantos, and got the only perfect mark I ever received in university- I wrote it from the point of view of a private eye, like Brawne Lamia in the books.  In fact I poosted the essay over at the Cave a few months ago.
Anyways, the reference to the sfumata was just a throwaway thing, but I wanted to learn more so I googled it, found a german page and got google to translate it for me.  The result:
 
"Sfumata is called the black or white smoke, which ascends after a Papal election of the burned voting cards from the Konklavesaal and which spectator at the Peter place in Rome of the respective conditions of the tunings informs."