This year the first round judging consists of rating a 300 word (max) "pitch" in which each author describes his or her book and why someone would want to read it. Those who make the cut on that round will have a 5,000 word excerpt of their novels rated. Submissions stop on February 8 or when they hit 10,000 books submitted, whichever comes first, so check it out fast if you're interested!
One caveat: Amazon makes everyone get a CreateSpace account to enter the contest. Even though there's no requirement to self-publish if you don't win, that kind of shows their motivation right there.