The movie made an estimated $16.7 million in theaters yesterday, despite being a kids' movie opening on a school day; according to Variety, we won't know how much of that comes from 3-D showings until tomorrow, but the Hollywood Reporter suggests that it might be a lot:

[T]he PG-rated pic is playing in 3-D on just over 2,000 of those [4104] U.S. and Canadian screens. So it was pretty impressive that early estimates had the 3-D venues accounting for just over half of the Friday grosses on "Monsters."

Estimates as to how much the movie is going to make over the course of the whole weekend range from $50million ( to $60million, but Nikki Finke is suggesting that we should expect it to fall somewhere around $57million (Slashfilm is guessing $56million), which would make it not only easily the biggest 3-D opening ever (beating previous top movie Spy Kids 3-D by more than $20million), but also the third most successful March opening for any movie, replacing Watchmen after less than a month in the #3 spot. Maybe Warners should concentate on the PG merchandising sweet spot from now on after all...

In its second weekend, Batman Begins only lost about 44 percent of its box office take, compared with a 63 percent drop-off for Batman And Robin. (And Superman Returns had a 58.5 percent drop-off.) So a lot depends, for the Hulk, on word-of-mouth and reviews. Can the Hulk crush Maxwell Smart this weekend? Few reviewers seem to be saying the Hulk is as great as Batman Begins, and it's possible most of the die-hard fans have seen TIH already. My guess is Hulk will end up doing almost as well as Superman Returns, which is nothing to sneeze at.

The other big surprise success of the weekend was M. Night Shyamalan's much-maligned The Happening, which scored $30.3 million, better than Unbreakable and Lady In The Water. The film will probably make back its $50 million budget, but its success may just hasten the slow death of Shyamalan's career, if the people who saw it decide never to brave one of his movies again. [Box Office Prophets and Box Office Mojo]