Xbox live has been re-built from the ground up to suit this new Next-Generation console. Many features have changed, and these are some of the major ones.

-Accounts and Achievements will transfer over (Confirmed)
-XBLA Purchases will not be transfered (games) (Confimed)
-Friends List Maximum moved from 100 - 1,000 100 - Unlimited(in relative terms 5-10k friends)(Confirmed)
-One Xbox Live Gold Membership Applies to all accounts (Confirmed)
-Your "Family" whether they live with you, are 3,000 miles away, or they aren't even related to you, can be added to your family group of 10 and your games can be accessed by 1 person at a time, and they will be able to play that game with you. They just have to download it. (Details are a little fuzzy, But confirmed.)
-300,000 Total servers(Confirmed)
-In a FAQ someone asked about the pirce of gold and microsoft stated: "It will remain the same price starting at $5 a month" (Not yet confirmed but hinted in the Confidential Micro soft report.)
-Larger Multiplayer (Confirmed)
-Unlimited Cloud Storage (Confirmed)
-Cloud Computing (Confirmed)
-New Reputation system based on how you behave/Play a game (Confirmed)
-New Living achievements that give rewards and allow developers to add new ones when ever they wish (Confirmed)
-24 Hour Check-In (Confirmed)
-Your Xbox live gold also applies to the 360 (Confirmed)
-1 Month Free Gold included on all consoles (Confirmed)
-Twitch.TV integration
-I'll Add more later.

-24 Hour Check-in to play offline: This has been issued to allow the console to properly run along side with cloud to make sure your features continue to work correctly.(Confirmed)
-DRM/Used game policy: This has been confirmed i shall not explain any of that here if you'd like to know more please ask, But this system was confirmed by a Microsoft Engineer to help prevent, Faulty/Laser burned/strachted games from being distributed, and also stated by him to stop the low amount of money given to the player for their $45+ Game, and also to allow the developers to now get money from used games if they wish, because they never got any profits off of used game. To share games they have instated a new system read it under the "Family" Group policy. But to share disc based games you can only give once to one person and they have to be a friend for 30 days on live.(Confirmed)
-Xbox Live Gold membership Policy: Allows one gold account to apply its gold to all accounts on the xbox one and your account on the 360 (Confirmed)
-"Family" Sharing Group Policy: Add up to 10 friends to give them access to your game library. Only one can play your library at a time, but they can play the same game as you. They must download the game though. But this allows a new and improved sharing method. No Disc Need to be given. You just add them to your "Family" On your account. They could be 5,000 miles away! and not even family! (Getting really fuzzy after major nelson answered my question on twitter, but there considering adding it so they can play multiplayer, But really i can still say Confirmed)
-Kinect Privacy Policy: The connect can be turned off but must remain connected. So unless you have a problem with a machine watching you masturb*T* then don't worry. (Confirmed)
-Requirements Policy: Needs and HDTV Capable of 720p/HDMI Plug in, and broadband internet, (ISP FEES APPLY, Which means if you go over your bandwidth cap if you have one they can't be held responsible) (Confirmed)
-Advertisement Policy: This one made me laugh, someone asked microsoft if they would allow other company's to advertise on the xbox one dashboard. Microsoft replied by telling them "We already have a product like that, but with 48 million people on it, Its called an Xbox 360, so yes there will be no advertisements. You customize your dashboard how you want" (Confirmed)
-3rd Party Accessories Policy: Microsoft stated no current-gen accessories will work, but any 3PP headsets for current gen, currently is being worked on for a possible adapter to work with next gen consoles. But your 3pp wired remote might work since its usb. But there will no longer be any 3PP Next Gen Controllers. ATM MS is working on a universal remote for entertainment on the xbox one but hinted at being able to use your current one if you have one. (Fuzzy, But otherwise Confirmed)
-Banned Policy: If you are banned you must re-purchase your games, since you loose the contents license. But its just another reason not to get banned (Fuzzy, but Most likely Confirmed)(This is no longer confirmed or mentioned)
-I Shall add more soon