While there have been feature films shot in 4K (e.g. GAMER, DISTRICT 9), there is a massive gearing up with 4K projectors on the way, that will make Fincher's next flick an amazing resolution experience for a greater audience. There wasn't much revealed about the film itself -- except that at the convention may have been the first public preview of footage.
Can't wait for a teaser/trailer, which should hit the web within a reasonable time. And maybe... it will be the first time we're getting a 2160p quicktime trailer?!