With an announcement from Major Nelson, Microsoft has announced the opening of registration for the Xbox 360 System Update Preview. The program will only be open to those owners in the U.S. and it seems as if it will not be tested in other regions.

Those interested in registering for the preview are apparently going to be testing the upcoming System Update, as well as an updated disc format. While little is known about the exact nature of the new disc format, some are suspecting that the new disc format could be an effort to extend the amount of data that can be stored on a typical Xbox 360 dual-layer DVD (beyond the 8.5GB/8.7GB that is normally found in Xbox 360 games today).

Of course, the exact nature of the System Update and new disc format are unknown, but those accepted into the preview program will be sent a copy of Halo: Reach as part of the program. It is expected that the update will be contained on the disc as well as new disc format for testing. Beyond getting a copy of Halo: Reach as part of the preview testing, it is possible that participants could also get other rewards.

According to Major Nelson, chances are good that you can get into the testing, as Microsoft is apparently looking for multiple thousands of people to take part. The test is open to both Silver and Gold members of Xbox Live, but priority will be given to gold members first.

The need for larger disc storage capacity seems to be something that Microsoft is exploring due to the fact that game developers are building larger titles that either need multiple discs on the Xbox 360 or have to be altered to fit in the current available disc space. (The PlayStation 3 does not suffer from this issue, as its Blu-ray drive can read both 25GB and 50GB discs.) It is difficult to say how Microsoft might be able to achieve more storage on a DVD beyond the 8.5GB/8.7GB that is the standard.

While some sources suggest that triple or quad layer discs might be possible, we doubt that it is without a firmware update to the drive itself; and even then we question whether the DVD drives in older Xbox consoles will have the ability to read a triple or quad layer disc. Other sources we have spoken with suggest that the new format might have nothing to do with storage at all, but might instead be a new format that Microsoft would like to use to prevent reading or copying of the discs for their console. Right now it is difficult to say what Microsoft might be up to with this new disc format.

U.S. Xbox 360 owners can visit the Microsoft Connect site to register by clicking here.