Rebecca Keegan, author of The Futurist: The Life and Films of James Cameron has written a pretty convincing “for your consideration” piece about why Avatar should win for Best Editing, rather than the Ace Eddie winner, The Hurt Locker on Vanity Fair’s Little Gold Men:
Unlike for most films, Avatar’s editing process began the moment Cameron called action. An Avid editing suite sat stage-side at the spare Los Angeles warehouse where Cameron shot the performance-capture portions of the movie. Instead of dailies, the director watched minutelies: he reviewed every single shot in the moment. Cameron had almost limitless options editorially because of the manner in which he was shooting. In a traditional live-action film, when multiple actors are in a scene, the editor is limited to the performances in a particular take. But Avatar’s editors could combine different takes. In one scene, they might choose Sam Worthington’s Take-Six, for instance, and Sigourney Weaver’s Take-Two. While this provided tremendous flexibility, it was also hugely complicating. And it was just the first of many edit steps.
There is no doubt that both The Hurt Locker and Avatar were both expertly edited.  Keegan