Andrew Huang wrote a book a few years back called Hacking The Xbox. He's an expert on the subject. He's such an expert, in fact, that federal prosecutors are trying to stop him testifying in a mod chip court case.
Courtesy of a report on Wired, Matthew Crippen is facing three years in prison if convicted of servicing Xbox 360 consoles and installing mod chips on them, offences which violate the United States' Digital Millennium Copyright Act.
Huang is willing to testify on Crippen's behalf, arguing that installing a mod chip does not in itself constitute a violation of copyright. He points towards a recent U.S. Copyright Office decision to allow the "jailbreaking" of Apple's iDevices as precedent for this; if they can be legally modified to allow third-party applications, so too should game consoles.
Federal prosecutors, however, have called for Huang to be barred from testifying on the grounds it would be "legally irrelevant".
I don't know. Seems pretty damn relevant to me.