Stiller spoke to MTV over the weekend he confirmed that he is working with Iron Man 2 and Tropic Thunder writer Justin Theroux on the script.  He also gave us an idea of what the story will be.

"We have a new story idea that we feel excited about and we're going to try to go forward," he said. "The beginning of the movie is [set]... 10 years later, and Derek & Hansel are literally forgotten. Nobody even knows who they are, so they have to re-invent themselves."

The rumors previously had Jonah Hill coming on board as a villain, perhaps replacing Will Ferrell's Mugatu character, but don't count Ferrell out yet.  "If Will says yes, he definitely has to be a part of it," Stiller said. "To me, Mugatu is one of the classic screen villains of all time."

Judging from the fact Stiller said it has Derek and Hansel reinventing themselves it seems that Owen Wilson will be a part of this picture and I don't see how Ferrell could possibly turn down an opportunity to play Mugatu again.  A Zoolander movie without Hansel and Mugatu just wouldn't be the same.  It would be like having to go through life without being really, really ridiculously good looking.  Stay tuned for more details as they surface.