Penn's first words upon taking the stage to accept his prize for playing the slain gay-rights pioneer were: "You commie, homo-loving sons of guns."
Kate Winslet, meantime, has taken best actress for the Holocaust-themed saga "The Reader," while best-picture favorite "Slumdog Millionaire" has cruised to seven Oscars, including best director for Danny Boyle.
Heath Ledger is the supporting-actor winner for his demented reinvention of Batman villain the Joker in "The Dark Knight," becoming only the second actor ever to win an Oscar posthumously.
The supporting-actress trophy has gone to Penelope Cruz as a tempestuous artist in Woody Allen's Spanish romance "Vicky Cristina Barcelona."
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