In January Sony pictures is projecting an uncompressed version of Spider Man 2 in Hollywood, California. They use shared storage solutions from SGI.. pretty exciting stuff and clearly the wave of the future.

http://videosystems.com/pressreleases/4K_Sony_Screening

Spider-Man 2 was not post-produced in 4K. The plates were scanned @4K and recorded at 2K. Nearly 60% of the film is visual effects shots - which were all done at 2K with the final master being 2K uprezzed to 4K before printing back to film. So this movie will look pretty much the same on both 2k and 4k projection systems.

I don't see what the fuss is about...

There is the possibility that while you won't get more resolution per-se, you will not notice any pixel or grid "patterns" on a very large screen like you will with lower resolution systems. In other words, you could probably sit in the first couple rows and not get the objectionable pixel patterns that many see with the 1K and even sometimes the 2K solutions.

The "screendoor" patterns will be better with 4K only if the fill factor on the 4K chips are comparable with the 2K chip's fill factor (~92%)