This is... unreal. Right at the bottom of one section of the big list of policies Microsoft just released for Xbox One is a little detail about how you'll be able to share games with your friends.
Turns out you'll only be able to share each one with only one person. Ever.
Give your games to friends: Xbox One is designed so game publishers can enable you to give your disc-based games to your friends. There are no fees charged as part of these transfers. There are two requirements: you can only give them to people who have been on your friends list for at least 30 days and each game can only be given once.
So if I give a game to my friend, it can never be given to anyone again. Unbelievable. Hope you weren't planning on sharing Xbox One games with your friends!