Marvel Studios' first production and this summer's current top-grosser Iron Man, has been so successful, grossing over $560 million worldwide, that it was a foregone conclusion that a sequel would happen sooner rather than later. What might be surprising is that according to Variety, they're changing writers for the second movie, going with actor/filmmaker Justin Theroux to pen the sequel, which is planned for a late April release in 2010.
While Marvel Studios negotiates with director Jon Favreau and Robert Downey Jr. to bring them back for the sequel, they've hired .Theroux, who some might know from his acting roles in McG's Charlie's Angels: Full Throttle and HBO's "Six Feet Under." He also wrote and executive produced Ben Stiller's upcoming war comedy Tropic Thunder (also starring Robert Downey Jr.), and presumably Marvel saw that he could write comedy and action suitable for shellhead's sequel. (Marvel Studios themselves haven't commented on any of the developments on the sequel as of yet.)
Other than writing TROPIC THUNDER (his screenwriting debut), he most recently made his directorial debut with 2007's DEDICATION (starring Tom Wilkinson and Mandy Moore)