Robert Plant and Alison Krauss were the big winners at the 51st annual Grammy Awards at Los Angeles' Staples Center, tallying five trophies, including album of the year for the Rounder project "Raising Sand" and record of the year for "Please Read The Letter."

"We are thrilled and very grateful to everybody who is excited for us," Krauss said. "I'm bewildered," Plant said. "In the old days we would have called this selling out -- but it's a good way to spend a Sunday."

The wins came on top of their victories for pop collaboration with vocals for "Rich Woman," as well as best country collaboration with vocals for "Killing the Blues" and best contemporary folk/Americana album. Krauss and Plant performed both "Rich Woman" and "Gone Gone Gone (Done Moved On)" during the show.

"This project has been spectacular from the beginning," Plant said. "We're very proud of the job T-Bone Burnett did for us to make it so good." The album of the year honor was presented by Green Day, who also announced the title of their new album, due in May, will be "21st Century Breakdown."

Lil Wayne won rap album of the year for "Tha Carter III" as well as best rap solo performance for "A Milli," rap song for "Lollipop" and rap/sung collaboration for "Swagga Like Us" during the pre-telecast. The artist, who joined Allen Toussaint, Terence Blanchard and Robin Thicke for a musical salute to New Orleans, led the nominee field going into tonight with nods in eight categories.

U2 kicked off the broadcast by performing its new single, "Get on Your Boots." The first major award of the night, song of the year, went to Coldplay for "Viva La Vida," which the group performed as part of a medley that began with surprise guest Jay-Z rapping on "Lost." While accepting, drummer Will Champion jokingly apologized to Paul McCartney for "blatantly recycling" the Beatles' outfits from the "Sgt. Pepper's Lonely Hearts Club Band" era.

The song also won best pop performance by a duo or group with vocals during the pre-telecast, and Coldplay later won best rock album for "Viva La Vida or Death and All His Friends." "We're not, of course, the heaviest of rock bands -- you may have noticed," frontman Chris Martin said. "We're kind of the limestone of rock bands. Not as hard, but still charming."

Whitney Houston made a surprise appearance to present Jennifer Hudson with the trophy for best R&B album for her self-titled Arista debut. Hudson, whose mother, brother and nephew were murdered in Chicago last fall, was overwhelmed by emotion as she accepted the Grammy. "I would like to thank my family in heaven and those who are here today," she said. The artist later performed "You Pulled Me Through" with the help of a choir.

Trumping the Jonas Brothers and Duffy, 20-year-old British vocalist Adele was a surprise winner for best new artist, having already won best female pop vocal performance for "Chasing Pavements." She later performed the song with Sugarland.

There was drama before the Grammys even began, as Rihanna canceled her performance about a half-hour prior to the telecast. Speculation is rampant that the move is connected to a domestic battery incident involving her boyfriend, R&B star Chris Brown, early this morning in L.A. A segment with Brown performing his hit "Forever" was also scrapped; Brown turned himself in to local police around 7:15 p.m. PT.

Al Green, Justin Timberlake, Keith Urban and Boyz II Men gave an impromptu performance of "Let's Stay Together" in Rihanna's place. Other performances included Radiohead playing "15 Step" with the USC marching band, Dave Grohl drumming with McCartney and his band on "I Saw Her Standing There," an extremely pregnant M.I.A. joining Jay-Z, Lil Wayne, Kanye West and T.I. for "Swagga Like Us," Carrie Underwood with "Last Name," which earlier won best female country vocal performance, and a Kid Rock medley dedicated to Lynyrd Skynyrd keyboardist Billy Powell, who died late last month.

Teen queens Taylor Swift and Miley Cyrus joined up on Swift's "Fifteen," while Neil Diamond led a sing-a-long on "Sweet Caroline." The Jonas Brothers played "Burnin' Up," and then teamed up with Stevie Wonder to sing "Superstition." West joined Estelle for their Grammy-winning "American Boy," and newcomer Katy Perry delivered a saucy, theatrical performance of "I Kissed a Girl." There were also multi-artist tributes to the Four Tops and Bo Diddley.

Sugarland won best country performance by a duo or group with vocals for "Stay," having already won best country song for it during the pre-telecast. "I told myself I was going to be cool because Paul McCartney and Coldplay are here," said lead singer Jennifer Nettles. "I'm so not cool."

Neil Portnow, president and CEO of the Recording Academy, took a political bent in his comments, noting that President Barack Obama is a two-time Grammy winner for the spoken word performance for his books, and that the Academy will continue to push for the enactment of Performance Rights Act. In addition, he asked Obama for the development of a cabinet-level position dedicated to culture and the arts.

There was also some reunion news during the broadcast. Before presenting Coldplay with best rock album, the members of Blink 182 announced they were getting back together after a four-year hiatus. "We used to play music together, and we decided we're going to play music together again," said drummer Travis Barker, still with his arm in a sling following his survival of a deadly plane crash last year.

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Here are the Grammy Awards presented during the telecast:

Best R&B album: "Jennifer Hudson," Jennifer Hudson
Best country performance by a duo or group with vocals: "Say," Sugarland
Song of the year: "Viva La Vida," Coldplay
Best pop collaboration with vocals: "Rich Woman," Robert Plant and Alison Krauss
Best rock album: "Viva La Vida or Death and All His Friends," Coldplay
Best new artist: Adele
Record of the year: "Please Read The Letter," Alison Krauss and Robert Plant
Best male pop vocal: "Say," John Mayer
Best rap album: "Tha Carter III," Lil Wayne
Album of the year: "Raising Sand," Robert Plant and Alison Krauss