The Iron Man 2 news was expected, but the Avengers news was still up in the air. Today, Marvel announced that Robert Downey, Jr. will indeed play Tony Stark/Iron Man in the Avengers movie. Also, Favreau, who directed Iron Man with near-perfect success, will executive produce the Avengers movie. I’m glad he’s involved, but I honestly wish he was directing it. Iron Man was the best comic-to-film adaptation I can remember, and I’m excited to see Marvel build their team of heroes in the cinematic Marvel Universe.
From superherohype.com:
As part of his four picture deal with Marvel Studios, Robert Downey Jr. is appearing as Tony Stark in THE AVENGERS motion picture, as well as reprising his starring role as the larger-than-life leading character in IRON MAN 2. Jon Favreau will return to direct the sequel to the blockbuster IRON MAN, which to date has grossed over $578 million worldwide, as well as executive produce THE AVENGERS.
Posted by Allen 
