Well, it turns out, at present, that there isn't an Authority movie.
On the one hand, an Authority movie, done properly, would be really cool. On the other hand, Watchmen was done properly, at least in my opinion, and people still bitched. An Authority movie would be much, much more problematice than Watchmen.
For starters, the first story arc starts of in media res. Hollywood LOVES rehashing origins for comic book characters, which is hard to do with the Authority.
Then, you have Apollo and the Midnighter. As two of the most prominent and popular characters, they would be a natural focus for marketing and merchandising. Unfortunately, they're gay. Now, America has come a long way, but I don't believe we've come far enough that Hollywood is willing to have gay characters as action heroes in a big budget blockbuster.
And then, of course, there's the villains. Evil superpowerd Asians, dimensional-traversing alien rapists, and God... Yeah, I'm guessing they'd drop all that for a more traditional, bland villain.
Honestly, I think it's for the best that there won't be a movie anytime soon.