Apple sold 5 million iPhones the first weekend.
Assuming that the three models averaged out to a ticket price of $749, (that's the price of the unlocked 32GB model, which should be close to what Apple gets from the cell phone carriers too.) That would be $3.7 billion for the opening weekend of "iPhone 5: the Movie"*.
According to Wikipedia, and adding up the numbers, the top 10 worldwide opening movies since 2002** combined would be about the same $3.7 billion. Nice.
* Though I kinda hope they'd name it "iPhone V: 4 Inches of Retina". #iphone5themovie
** I doubt any older movies would be in that particular not-adjusted-for-inflation list.