If you're a Xbox LIVE Gold subscriber, you can head into Marketplace right now and pick up a free premium theme to spruce up your 360. Thanks for playing! Love, Bungie.
"ODSTs aren’t the only ones getting their hands on upgraded gear to prepare for the upcoming Firefight. Available only for a limited time and free of charge for Xbox LIVE Gold Subscribers, this expertly crafted Halo 3: ODST Premium Theme will get your Xbox 360 ready for a combat drop into the city of New Mombasa."