Coldplay frontman Chris Martin to guest on Kanye West album

Coldplay is busy working on its fourth album, but frontman Chris Martin has signed on to join rapper Kanye West on his next album, Graduation. Martin will sing on the track "Homecoming," which West told Billboard is likely to be the first single from the set. The album, West's third, is expected out in the winter of 2007.

Martin has also made guest appearances on recordings by former Echo & the Bunnymen frontman Ian McCulloch, Canadian singer-songwriter Ron Sexsmith, and on rapper Jay-Z's "comeback" album, Kingdom Come, in 2006. A contribution to Nelly Furtado's latest album, Loose, was disallowed by his record company, Capitol Records.

Martin is married to actress Gwyneth Paltrow. The couple have two children.

There's no word yet on when the next Coldplay album will be released.