The film's director, Martin Scorsese - who has been waiting many years to clutch the coveted statue - walked off with the award for Best Director, taking the prize for his crime epic after five previous losses.
"Could you doublecheck the envelope?" said Scorsese, who had been the greatest living American filmmaker without an Oscar. He also had never delivered a best picture winner before, despite crafting such modern masterpieces as "Raging Bull" and "Goodfellas."
Scorsese received his Oscar from three contemporaries and friends, Steven Spielberg, Francis Ford Coppola and George Lucas. "So many people over the years have been wishing this for me," Scorsese said.
In an evening when no one film dominated as Oscar shared the love among a wide range of movies from around the world, three of the four acting frontrunners won: Best Actress Helen Mirren as British monarch Elizabeth II in "The Queen"; Best Actor Forest Whitaker as Ugandan dictator Idi Amin in "The Last King of Scotland"; and Supporting Actress Jennifer Hudson as a soul singer in "Dreamgirls."
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2The other frontrunner, Eddie Murphy of "Dreamgirls," lost to Alan Arkin in "Little Miss Sunshine."
"For 50 years and more, Elizabeth Windsor has maintained her dignity, her sense of duty and her hairstyle," said Mirren, 61, who has been on a remarkable roll since last fall as she won all major film and television prizes for playing both of Britain's Queen Elizabeths.
"She's had her feet planted firmly on the ground, her hat on her head, her handbag on her arm and she's weathered many many storms... If it wasn't for her, I most certainly wouldn't be here. Ladies and gentlemen, I give you the queen," Mirren said, holding her Oscar aloft.
"The Departed" led the evening with four Oscars, also winning for adapted screenplay and editing.
The Oscars had their most diverse and international scope ever, with wins for two black actors and global dramas that included "Pan's Labyrinth," "Babel" and "Letters From Iwo Jima."
The soft-spoken Whitaker, 45, won for an uncharacteristically flamboyant role as the barbarous yet mesmerizing Amin.
5"When I was a kid the only way I saw movies was from the back seat of my family's car at the drive-in movie," Whitaker said. "It wasn't my reality to think I would be acting in movies, so receiving this honor tonight tells me it's possible. It is possible for a kid from east Texas, raised in south central L.A. and Carson, who believes in his dreams, commits himself to them with his heart, to touch them and to have them happen."
Arkin, 72, played a foul-mouthed grandpa with a taste for heroin in "Little Miss Sunshine," a low-budget film that came out of the independent world to become a commercial hit and major awards player.
Hudson's Oscar comes for what is her very first movie, playing a powerhouse vocalist who falls on hard times after she is booted from a 1960s girl group. The role came barely two years after she shot to celebrity as an "American Idol" finalist.
"Oh my God, I have to just take this moment in. I cannot believe this. Look what God can do. I didn't think I was going to win," Hudson, 25, said through tears of joy. "If my grandmother was here to see me now. She was my biggest inspiration."