Iron Man 2 director Jon Favreau told the Los Angeles Times that work has begun on the sequel:
I just talked to Jon Favreau a bit ago, and he said that while there hasn’t been an formal announcement on the sequel to “Iron Man,” he’s begun developing it. “We’re working on it now,” he said, “which hasn’t been officially announced. It will be released in 2010.”
Iron Man has grossed over $570M worldwide and is currently the year’s second highest-grossing film at $317.15M. The sequel will hit theaters on April 30, 2010. Justin Theroux (Tropic Thunder) is writing the script, while Robert Downey Jr. will return as Iron Man/Tony Stark and co-stars Gwyneth Paltrow and Terrence Howard are expected to return.