Update: Some of our loyal commenters are telling us that a modified Xbox 360 console is not required for the Battlefield: Bad Company beta leak. However, considering the online nature of this "demo" we'd recommend you'd be wary of attempting this process -- lest the ban hammer be used to knock your console offline for good.
Tipsters are telling us that the Battlefield: Bad Company beta has not only leaked to online download sites but that it may also be playable via a burnt DVD-R, much like the demo for Guitar Hero III. The ability to clone the download of the beta and release it to other consoles also reminds us of the Call of Duty 4 beta glitch which allowed gamers to use the account recovery feature to circumvent the barriers in place of people who hadn't been selected to participate in the closed test.
This situation appears to be more serious as download sites are claiming users will have to modify their console in particular ways in order to run the download from a DVD-R. Of course we remind you that any modification of your Xbox 360 console will void your warranty and can lead to an outright ban of all Xbox online services, including playing games over Xbox Live.
Don't do it. Stay in school. This is your brain on drugs.
You get the idea.