UPDATE - SUNDAY: "Iron Man 3" has scored the second-highest opening weekend estimate of all time with $175.3 million, behind only "The Avengers". This comes on top of the $504.8 million the film has earned outside the United States so far, leading to a global total of $680 million.
ORIGINAL - SATURDAY: Including a whopping $15.6 million in Thursday previews and midnights, the third "Iron Man" film opened to a whopping $68.31 million on Friday - the eighth all-time opening day record.
That's considerably up on "Iron Man 2" which scored a $51.2 million opening day, but behind last year's major superhero films "The Avengers" with $80.8 million and "The Dark Knight Rises" with $75.7 million.
At present, "Iron Man 3" is on its way to towards an opening weekend around $160-170 million - possibly the second highest of all time. I'll keep this article updated as the numbers come in.