Oscar Triumph For Actor Hoffman
Actor Philip Seymour Hoffman has won the best actor Oscar for his role as author Truman Capote, beating Brokeback Mountain rival Heath Ledger.
The Capote star, 38, paid tribute to his mother, and said he was "overwhelmed" by the honour.
British hopes were riding high at the annual Academy awards after winning three Oscars, including best supporting actress for 34-year-old Rachel Weisz.
Cowboy romance Brokeback Mountain is tipped to take the night's key awards.
King Kong and Memoirs of a Geisha both have three wins so far in technical categories.
Cult comedian Jon Stewart, of The Daily Show, is hosting the annual event for the first time in a bid to attract younger viewers to the ceremony, but contrary to predictions steered away from controversy in his opening gambit.
Instead he poked fun Hollywood's penchant for liberalism, touting the Oscar telecast as a rare "place where you can watch all your favourite stars without having to donate any money to the Democratic Party."
Low budget films like Brokeback Mountain dominate this year's Academy Awards, with only Steven Spielberg's Munich - a fictional drama about the aftermath of the the 1972 Olympics massacre - costing more than $15m (£8.5m).
Clooney's Good Night, and Good Luck, Capote, a biopic of In Cold Blood author Truman Capote and racial drama Crash complete the five best film nominees.
Triple nominee George Clooney won best supporting actor, the first award of the night, for his role in oil drama Syriana.
Clooney proved a popular win, after a triumphant year that has seen him nominated for three Academy Awards including best director and best original screenplay for Good Night, and Good Luck.
"So I'm not winning director," quipped the 44-year-old Hollywood heart-throb.
"I do not know how you compare art," said Clooney of his fellow nominees including Brokeback Mountain's Jake Gyllenhaal and Matt Dillon.
"They are stellar performances and wonderful work, and I'm truly honoured, to be up here."
Weisz, who won the Oscar for her role in The Constant Gardener, called the award "a tremendous honour" and paid tribute to her "luminous" co-star Ralph Fiennes.
Earlier in the evening, UK hit Wallace and Gromit: The Curse of the Were-Rabbit won the best animated feature film, and Six Shooter picked up best live action short.
The animation Oscar marks creator Nick Park's fourth Academy Award, but his first for a feature film.
"Someone once said if you make a bad film you make it alone, if you if you make a great film everyone made it with you," said Steve Box, of Aardman Animations on stage with Park.
"We made a great film, guys."
"Cracking cheese Gromit!" said Park and Box together.
Capote star Philip Seymour Hoffman is favourite to pick up the best actor award, ahead of Heath Ledger and Joaquin Phoenix, who stars as late country singer Johnny Cash in Walk the Line.
Terrence Howard, who appeared in Hustle and Flow, and David Strathairn, who plays broadcaster Edward R Murrow in Good Night, and Good Luck, are also nominated.
Reese Witherspoon is the favourite to win best actress for her portrayal of Johnny Cash's wife June in Walk the Line.
The 29-year-old star vies with Britain's Keira Knightley, nominated for her role as Lizzie Bennet in Pride and Prejudice, Dame Judi Dench, Felicity Huffman and former winner Charlize Theron.
