You would think that the Vatican would know that he wasn't going to show, (in reference to the Vatican cameras below):
From Yahoo! News - Pope Skips Appearance at His Window:
" Pope John Paul II skipped his traditional appearance at his window overlooking St. Peter's Square the day after Easter, following a Holy Week during which he was unable to speak.
An appearance Monday -- a national holiday in Italy -- had not been confirmed because of John Paul's convalescence from throat surgery to ease a breathing crisis, although he had kept the appointment to bless pilgrims throughout his 26-year papacy.
Vatican TV cameras zoomed in on the pope's window at noontime, but the curtains remained closed."