During the Microsoft conference, Phil Spencer made an empathic point that he wants to make the Xbox One and Windows 10 one big happy family. Today the team announced Xbox Play Anywhere. From now on, any Microsoft exclusive that you buy either on the Xbox One or your Win 10 PC will directly transfer over to your other device for free. For example, if you buy Gears 4 on the Xbox One and also want to play it on your PC, you will get the game for free.
They also want to make cross-play available to the majority of their games. Already Rocket League and Killer Instinct have cross-play, but Gears 4 is the main title that they showcased. This was the best announcement in my eyes, as Microsoft is very adamant on bringing all Microsoft enabled devices together as one.