While Final Fantasy XII's gambit system (read: ability to assign AI tasks with provisos) wasn't perfect, it was ahead of its time, especially for a console RPG.
Obnoxious marketing speak aside in the trailer, it does a decent job of explaining what the gambit system actually is, which a Dtoid commenter recently called "a tinkerer's dream." In tandem with the job system that lets you swap between 12 classes (and the more open International Edition enhancement), you can also program parameters for your AI, with percentages and specific types of skills.
It's probably the best part of the game, and I'm looking forward to seeing how fondly I remember the rest next month. In the meantime I was able to mess around with an early preview version and the new fast-forward feature.