That's right, a little taste of the good stuff LONG before the game hits shelves.
In addition, there will be a special one-time TV ad on Monday Night Football on December 4th, so get those DVRs ready. If you miss it, it will be available in High Definition on Marketplace soon after airing.
Pieces of the Halo 3 storyline and gameplay were also presented, although they are in typical PR fluff:
Next-generation high-definition visuals; enhanced artificial intelligence; an advanced real-time lighting engine; and new weapons, characters and challenges are just a few examples of the evolution of design and technology in Halo 3.
Working in concert with Xbox Live on Xbox 360, Halo 3 builds on the unique social multiplayer experience of Halo 2 and promises to expand the innovative and evolving online gameplay and community of Halo 2 on Xbox Live.
Below this text is a spoiler that reveals the story line, while not Earth shattering, read at your own risk. The font color is white, so highlight to see it:
In this third chapter of the Halo trilogy, Master Chief returns to finish the fight, bringing the epic conflict between the Covenant, the Flood and the entire human race to a dramatic, pulse-pounding climax.
A HUGE thanks to John Porcaro at Gamerscore blog for the news.