Microsoft's mysterious updated Xbox 360 disc format will add an extra 1GB of storage to the console's game discs. Current game discs use only around 6.8GB of a DVD's theoretical 7.95GB capacity, with the rest being filled up with gubbins such as anti-piracy measures. Digital Foundry speculates that Microsoft is either greatly reducing or outright removing the extra data. Extra space will allow developers to include more (or higher-quality) textures, sounds, movies, and the like in Xbox 360 games. If you're in North America and want to join Microsoft's testing for the new disc format, you can sign up now. Participants will receive a free copy of Halo: Reach for their troubles.