Hey, guess what, kids? They’re making a sequel to “Iron Man”! Yeah, gosh, I didn’t see that coming, too, especially when the first one only grossed, what, $500 million worldwide? Anyhoo. The surprise is that Marvel seems to have jettisoned the original writers of the first movie, and is set to replace them with one guy — actor-director Justin Theroux. Then again, this is Hollywood, and this is a big Summer Event Film, so my guess is that Theroux will get first crack, before Marvel brings in more writers to “tweak” his script.

THR has more on the switcheroo:

Theroux, repped by UTA and 3 Arts Entertainment, has story and screenplay credit, along with Ben Stiller, on next month’s DreamWorks action-comedy “Tropic Thunder.” He also is a producer on the movie.

Known primarily as an actor — he’s played everything from Jesus H. Christ (”The Ten”), John Hancock (HBO’s “John Adams”) and Evil DJ (”Zoolander”) to the hapless director Adam Kesher in David Lynch’s “Mulholland Dr.” — Theroux is on a career-changing tear. Last year he directed his first film, “Dedication,” which the Weinstein Co. released.

That’s a pretty impressive list of credits there. Who didn’t think Theroux’s turn as “Evil DJ” in “Zoolander” was Oscar caliber stuff? I know I did the moment I saw it!

Anyhoo. “Iron Man 2″ is gearing up for 2010 with Favreau confirmed back behind the camera. Get ready, kiddies.