Justin Timberlake and Al Green

Collaboration was the theme of the 51st Annual Grammy Awards on Sunday as artists as diverse as Coldplay and Jay-Z; Stevie Wonder and the Jonas Brothers; and Radiohead and the USC marching band teamed up for unpredictable performances of recent hits and old classics.

One of the wildest collaborations of all — Robert Plant and Alison Krauss — netted five awards, more than anyone else.

Al Green, Keith Urban and Justin Timberlake — a last-minute replacement for Chris Brown — set the cooperative mood with a soulful and polished version of Green's classic, "Let's Stay Together." Jay-Z joined Coldplay onstage to keep the collaborative spirit alive.

Other collaborations ranged from inspired to strange, but for the most part they worked: Paul McCartney and Foo Fighters frontman Dave Grohl; Miley Cyrus and Taylor Swift; and Ne-Yo, Jamie Foxx, Smokey Robinson and original Four Tops performer Duke Fakir.

One of the night's weirder combinations drew a quip from Blink 182's Mark Hoppus.

"Isn't it great to see the Jonas Brothers and Stevie Wonder back together again?" said Hoppus, who was joined onstage by unlikely collaborators: his former band mates. The group was making its first major appearance since reuniting in the wake of a plane crash that seriously injured drummer Travis Barker.

Whitney Houston made a surprise appearance to honor Jennifer Hudson with the best R&B album award for her self-titled debut.

"I would like to thank my family in heaven and those who are here today," said Hudson, whose mother, brother, and nephew were killed in a domestic case last year. She also won a standing ovation for a moving performance of "You Pulled Me Through," which ended with her fanning away tears.

The night's wildest performance was a rendition of "Swagga Like Us," by a foursome that Queen Latifah introduced as "The Rap Pack." T.I., Kanye West, Jay-Z, and Lil Wayne traded verses as M.I.A., who was due to give birth Sunday, bounced around the stage in a body-hugging, polka-dot and sheer outfit that highlighted her pregnancy. The song is built around a sample from her Grammy-nominated hit "Paper Planes."

New Orleans took over the stage late in the night — as they always do — as best-rap-album winner Lil Wayne brought Allen Toussaint and the Dirty Dozen brass band onstage after his own collaboration with Robin Thicke.

Plant, the former Led Zeppelin frontman, got looser with his acceptance speeches as the night wore on. He started out saying he and Krauss went into their roots-rock project with no expectations, and later joked that while the Grammys once seemed to him like selling out, he now considered them a pretty good way to pass a Sunday night.