Yesterday, Major Nelson was taking volunteers to beta test an updated Xbox 360 disc format. One of Digital Foundry’s sources confirms that it’s still the same DVD, just with less data taken up by security measures. DF suggests that up to 1GB more will be available to developers on the new disc format.
The DVD format the Xbox 360 uses has been seen as a limiting factor for some time, with Dan Houser of Rockstar Games pointing it out as a problem back in 2007 when he was developing Grand Theft Auto IV.