SO yeah, Bungie announced at 7:07 Pacific time their new game. Or rather, released a teaser of it!
You can check it out here:
http://www.bungie.net/News/content.aspx?type=topnews&cid=15574, or on the X-Box Live Marketplace!
Apparently the hardcore Halo fanboys with their intense mastery of the LORE have discerned that this has something to do with Orbital Drop Shock Troopers (since the ODST moto or w/e is at the end!) during the First and Second Battle of Earth between Earth & the Covenant. The game is called Halo 3: Keep it Clean, and it is a campaign expansion pack for Halo 3 that will take place on New Mombasa (the place where the teaser takes place in from the security camera footage), probably detailing the war between the two races.
A picture during the trailer that is SEEMINGLY random letters and numbers, reveals the release date:

Yay?
This looks interesting since it's EARLIER (it's a prequel to even Halo 1!!!), and on Earth for a change.