Grossing over $100 million in its first weekend, Marvel has already greenlit a sequel to Iron Man due in 2010. Also coming shortly after the sequel’s release in 2010 is a movie adaptation of Thor.

From the article:
Marvel plans to launch its 2010 film slate with the release of the sequel, Iron Man 2, on April 30, 2010, followed by the launch of Thor on June 4, 2010. Additionally, Marvel is planting its feature film stakes for summer 2011 with an Avengers-themed summer – a two-picture project which will debut on May 6, 2011 with The First Avenger: Captain America (working title), followed by The Avengers in July 2011.

Via Yahoo Finance