This is what he told me, in no uncertain terms: "Well, here's the real truth of it: we are going to do it. It's very, very probable. The script is not finished yet, and when the script is finished, we will go into production. I'm positive. "

...

http://www.maximumfun.org/blog/2009/02/jeffrey-tambor-on-arrested-development.html

How many years has this been going on now?

Will Arnett talks about the film...

Today though, Development star Will Arnettgave a little bit of insight into the status of the films production stating: “There’s no script as of right now, but it’s something that Mitch [Hurwitz] is actively working on and getting ready for, and we’re hoping to start shooting by the end of the year,” he revealed. “I know that’s one of the goals. There are a lot of pieces that have to come together. There are what, like, nine cast members plus various other people like Mitch and Ron Howard, and everybody kind of has to get their brain around this one delicious souffle.”

 http://www.killerfilm.com/articles/read/will-arnett-reveals-arrested-development-status-6406