Up until this summer, Justin Theroux was best known for his supporting turns in such movies as American Psycho and Mulholland Drive. Yet the actor recently tried his hand at writing with Tropic Thunder and it seems to have paid off because he's now in final negotiations to write Iron Man 2, according to The Hollywood Reporter. Director Jon Favreau is also in final negotiations to direct the sequel which has a planned release date of April 30th, 2010.