This is very high on the "whaaaaa?" list:

It’s an unlikely pairing, but it’s legit: Elton John sings on “Black Gives Way to Blue,” the title track on Alice in Chains‘ September 29th album. The song is a tribute to the band’s late frontman Layne Staley, who died in 2002 from a lethal speedball, and the collaboration was born when singer-guitarist Jerry Cantrell thought the track could use a little piano.

When a pal suggested Cantrell ring up Sir Elton John, “I remember laughing and saying, ‘Yeah, I’ll get right on that,’ ” Cantrell says in a statement. “But I decided it was worth trying and wrote Elton an e-mail explaining what that song means to us — that it’s a real, raw openhearted song for Layne.” The band sent John the track and were “blown away” when he quickly responded saying he was in. “Elton John is a huge influence on me as a songwriter and having him on that song is an amazing honor for us,” Cantrell adds.

John reveals that he’s been a “an admirer of Jerry Cantrell” for quite some time, and “couldn’t resist” the offer. “It was a great recording session with Alice In Chains for a beautiful song,” John says in a statement.

What's next, Aretha Franklin on the next Stone Temple Pilots disc? Actually, that's not such a bad idea...