Interesting take on this from Penny Arcade's Ben Kuchera, prompted by the brewing storm over Xbox One's game licensing system. In short, when you buy a game on disk from Microsoft, you're really buying a license to play it on your machine that's tied to your account. You can move that license around to play it at a friend's house, or you can give up the license (likely for some credit against new games) and never play it again. You can also give the disk to anyone you like and they can install it, but they can only play it if they buy a license. It seems like a solid idea, but it's complex for users to wrap their heads around, and it'll likely kill second-hand sales stone dead. Ben makes a good argument for this being a good thing, and it'll be interesting to see what developers do with the price flexibility that this affords them.
i'll be talking about this with Kyle on Doom Ray this weekend, so let me know your thoughts in the usual places.