With Iron Man waltzing past the $550 million mark worldwide, it’s no surprise that Iron Man 2 is taking shape fast. Jon Favreau, after an anxious few weeks for fans, is returning to direct, and Robert Downey Jr will once again be donning the old Shell Head. But there is a new boy in town, in the form of writer Justin Theroux, who’ll be taking over script duties.

If you don’t know that name and are vaguely wondering whether he’s the same guy as that TV presenter with the glasses, fear not. Justin (not Louis) Theroux is an actor-turned-writer who recently worked on the script for Tropic Thnuder with Ben Stiller and Etan Cohen (so perhaps Downey put in a good word for him). You may also remember him from such roles as “Evil DJ” in Zoolander. Joe in Six Feet Under and “Seamus O’Grady” in Charlies Angels: Full Throttle (but let’s not hold that against him).

The first film was written by Mark Fergus, Hawk Ostby, Art Marcum and Matt Holloway, so chances are that at some point someone else will be brought onboard this version for rewrites, but in the meantime, good luck to Theroux, and let’s hope he writes a scorcher for the planned May 2010 release.