Rihanna and Katy Perry are collaborating on a song, the Barbadian singer has revealed. "We're actually working on some music together...hell yeah!" Rihanna said, adding that the track will not appear on her upcoming Loud, due Nov. 16. Rihanna also said she hopes to hit the road with BFF Perry. "I would love to tour with Katy," she said. "She's a rock star." Lil Wayne is planning to release a mixtape and start working on tracks for Tha Carter IV upon his release from prison this week, the rapper said in an interview from New York's Rikers Island. "When I'm released, I'll be giving my musical attention to Tha Carter IV and promoting I Am Not a Human Being," he said. "I may drop a mixtape! You know me!" T.I. began his 11 month sentence in an Arkansas federal prison for parole violation yesterday. The rapper is back in jail after violating probation when he was arrested on September 1 in Los Angeles for drug charges. The Decemberists will release their sixth album, The King is Dead, on January 18, a rep for the band confirms to SPIN. (Previous reports indicated the album would come out on January 11.) The album features R.E.M.'s Peter Buck guesting on three tracks, "Don't Carry It All," "Calamity Song," and "Down by the Water." In advance of the release, the Decemberists are offering "Down by the Water" as a free download, which you can get below.\t Watch Jenny Lewis perform a sultry new song "Just One of the Guys" from a Halloween gig in New Orleans.