Marvel Studios mega-producer Avi Arad confirmed to MTV that last weekend, two-time Oscar winner Hilary Swank has filmed some top-secret scenes for Iron Man, the highly-anticipated superhero flick due in theaters next May. Arad admitted: "It's a cameo."

When asked about the rumor that Samuel L. Jackson will appear in the film, Arad said "I can't talk about that." Then after a few moments, the producer added "The Sam thing was supposed to be the biggest secret of them all," he shrugged. "It's amazing how it got out."

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Based on the long-running Marvel comic book series, Iron Man tells the story of Tony Stark, the enigmatic heir to the Stark Enterprises fortune. A driven inventor and executive who seems to have it all, Tony is haunted by his dark side. Though he commands his empire by day, by night he secretly becomes Iron Man, the living embodiment of decades of defense spending and innovation. Strapping on billions of dollars worth of state-of-the-art armor and weaponry each night to fight crime, terrorism and corporate espionage, Tony begins to crack under the strain of his fractured lifestyle and must ultimately confront the one enemy he can never beat -- himself.

Iron Man arrives in theatres on May 2nd, 2008.