The rapper is set to release Relapse, his first album since 2004, in May.
Eminem made a rare public appearance on Saturday to induct Run-D.M.C. into America's rock and roll hall of fame in Cleveland, Ohio.
The rapper looked well and slim, disproving rumours he'd put on weight during his time out of the lime light.
Eminem even wore the group's trademark black fedora and black leather jacket as he told the crowd how the rap posse changed his life.
"They broke away from the pack by being the pack," he said.
"They were the baddest of the bad and the coolest of the cool. There's three of them and if you grew up with hip hop like I did, they were The Beatles."
Nearly 5,000 fans partied in the balconies inside Cleveland's newly-renovated Public Auditorium as 1,200 VIPs dined below at tables costing as much £35,000 each.
'Way of life'
With two turntables and a microphone, Run-D.M.C. broke down the barriers between rock and rap.
With sparse, stripped-down lyrics above pounding beats, the trio of Joseph 'DJ Run' Simmons, Darryl 'D.M.C.' McDaniels and Jason 'Jam-Master Jay' Mizell changed rap in the 1980s by taking the realities of the streets to the suburbs.
Their remake and collaboration with Aerosmith on the rock band's Walk This Way changed modern music.
Red Hot Chili Peppers' Flea inducted Metallica into the Hall
"We were young guys with a new music that people thought was a fad, but we knew the culture was a way of life and we just lived it," McDaniels said.
"The music that we made then didn't just impact friends, it impacted a generation. So I guess that's what rock and roll does."
Any chance of a Run-D.M.C. reunion ended with Mizell's death in 2002, when he was shot to death in a New York studio. His murder remains unsolved.
"My baby is still doing it for me," said Mizell's mother, Connie, accepting the award on his behalf.
Other acts honoured this year included Metallica, guitarist Jeff Beck, soul singer Bobby Womack and veteran rhythm and blues vocal group Little Anthony And The Imperials.
Metallica were inducted into the hall of fame with a little help from Red Hot Chili Peppers' bassist Flea, who recalled being on tour and hearing Metallica on the radio for the first time.
"Whatever the intangible elements are that make a band the best, Metallica has them," he said.
"My mind was blown. It wasn't punk rock. It wasn't heavy metal. It just stood by itself.
"I didn't know what it was, but I knew it was a mighty thing."