The problem, I think, would be that if "we" succeed in hacking the 360, MS would be in a far better place for suing if we had looked at their source code. Reverse engineering and exploiting bugs in their software/games is a far better (but tougher) way of doing it.
If you look at their source code I would think you have to sign something stating that you may not misuse the knowledge or something like that.
Even if we look at the source code and doesn't use that info to breach the security of the 360, MS could always claim that we had. And who has the money to fight them? I think the source code is better left alone.
Tempting thou...
This is the same reason that the developers of Wine for Linux doesn't want to look at the leaked sources of Windows. They would be in deep trouble if they did.
This isn't some internet "h4xx0rz", this is the national archive of copyrights.
America's taxes pay for your right to source code.