After just two weeks it's already crossed the 1 Billion mark and it doesn't have any signs of slowing down. Titanic WW sales are at 1.835 billion. I think Avatar is going to have a shot at beating Titanic. If not it'll definitely be the second best selling movie of all time (LotR: Return of the King: 1.129 Billion).
That sure does shut a lot of people up claiming movies aren't as big as they use to be because of the internet.
Avatar currently at 1.018 Billion.