As previously announced, the new commercial for Halo 3 will air tonight. Sign-ups for the beta will also begin today.
Tonight during Monday Night Football on ESPN a new Halo 3 commercial will hit the airwaves. Using a mix of live action and CG, the commercial will last for 60 seconds and offer some idea of what the next game will be all about. You can catch it sometime between 7:50 and 8:20PM CST during the game or soon after on Xbox.com and the Xbox Live marketplace.
The beta sign-up form will also be appearing on the official website today. Scheduled for sometime in Spring of 2007, the beta will be for testing multiplayer modes only. North America, Europe and other regions should all have a chance to join the fun.
Source: Bungie.net