The disc is just storage now. You put it in, install it to the xbox, and then it activates to your Live ID. Then the disc is useless and you can give it to anyone you want. When they install it, it's not activated to their account, so they have to buy it. Owning the disc doesn't mean you own the game, you're just buying the storage and an activation at retail. Though I'm not sure how that initial activation is going to work.. will be interested to find out.