So we've been following this for a while, but here's some real news straight from Arrested Development creator Mitch Hurwitz himself: It looks like it will happen. And it may happen this year.
According to Entertainment Weekly, Hurwitz says:
"We've started that process, and it is our sincere hope to shoot it this year and get it out this year. That's what we're hoping, but a lot of things have to fall into place for that to happen. . . . I don't like to toy with the affections of our fans. They've been so supportive, and we're so grateful, so I kind of hate to answer the question until I can say, 'Yep, we've shot it; it opens next week.' Otherwise, it feels like we're toying with people, and we do not mean to do that. It has just taken a while to get it going."
No, seriously. This year? STOP MESSING WITH US, HURWITZ.