Yes, that's really him.
And in related news...
Wu-Tang Clan rapper Ghostface Killah (who goes by the hip-hop nickname Tony Starks and named his '96 debut "Iron Man") tells MTV he has a small role in Iron Man:
"I jumped in there for maybe 12 or 16 bars, nothing too major," Ghost downplayed before describing his scene with the film's star. "It was a good look for the kid because Robert Downey Jr. recognized me as soon as I seen him. He was like, 'Yo, Tony!' ... For him to recognize me, I was kinda surprised by that. I didn't know he even knew about the kid. ... We called each other Tony onscreen. I'm like, 'Tony Stark, I got your jet, I didn't mess it up.' He was like, 'I got the Bentley for you, I laced it up.' I had two girls with me, I was like, 'That's you [pointing toward the girls].' I sent two birds at him. It was a wrap for that scene. He's a cool dude and funny. Big up to Robert Downey Jr.
Dude's got skills, though!