Last week during the Video Games Live concert in Seattle Washington, the orchestra performed for the first time ever the theme from Halo 3: ODST. The Halo franchise has always been about atmosphere and mood, and Marty O'Donnel's music plays a huge role in that.
Super secret shaky cam ninjas were on hand to capture the music on video. Music on video? Yes. Music on video. Anyway - the theme only runs about a minute long but it sounds pretty familiar to the Halo universe. ODST will feature a full four player co-op campaign, during which, I'm sure you'll hear this pop up.
Wanna give it a listen? It's embedded right below.