“Terminator” fans showed their support for the franchise with $3 million at the box office for Thursday midnight screenings of “Terminator Salvation” in an early start to what should be a robust Memorial Day weekend.

Warner Bros. didn’t disclose how many theaters offered the 12:01 a.m. shows as it launched the fourth “Terminator” at 3,580 playdates domestically, with 50 venues added today. Fox’s “X-Men Origins: Wolverine” grossed nearly $5 million in 1,595 midnight runs on May 1, and in March, Warner’s “Watchmen” grossed $4.6 million at such midnight shows.

In a matchup of tentpoles aimed at different audiences, Fox launches “Night at the Museum: Battle of the Smithsonian” today at 4,096 domestic runs.

Tracking indicates both should wind up the weekend at more than $50 million, with “Salvation” banking on strong support among males while “Smithsonian” takes advantage of being the first famiy pic in the marketplace since “Monsters vs. Aliens.”

“Smithsonian,” which held its world premiere at the Smithsonian last week, is also launching at 161 Imax venues. The original “Night at the Museum” took in $18.3 million at Imax sites, or 7% of its $251 million domestic cume.

Paramount offers counterprogramming to the tentpoles with the spoof “Dance Flick,” opening today at 2,450 theaters.

And on the specialty front, Magnolia’s launching Steven Soderbergh’s “The Girlfriend Experience,” with porn star Sasha Grey portraying a high-priced call girl, at 30 playdates amid mostly positive notices.

Disney’s debuting the documentary “The Boys: The Sherman Brothers’ Story” at five locations. It’s an exploration of the troubled relationship between the siblings who composed such upbeat fare as “It’s a Small World” and “A Spoonful of Sugar”; “Smithsonian” star Ben Stiller’s an exec producer on “The Boys.”

Sony Classics opens Norwegian comedy-drama “O’ Horten” at 10 and period comedy “Easy Virtue” at eight, while Oscilloscope launched “Burma VJ” on Wednesday at one site.

And Summit expands caper comedy “The Brothers Bloom” into 52 markets after a solid opening last weekend of $90,400 at four screens.