"Right now, it’s on hold. There’s a script we like, but I don’t want to force it, because people who love that movie really love it, so I want to make sure we do the sequel the right way. Mike Myers did it well with the Austin Powers movies – they were all funny, and very ‘of their time’. And Zoolander is ‘of its time’, too, so it’s about how we could bring it up to date, to the present day."
http://www.shortlist.com/entertainment/films/ben-stiller-gets-serious(ish)