Xbox One September update is poorly named, as it has already been released, days before September even begins. The update adds several new features, most notably the Media Player, which allows users to view and listen to media stored on a USB device. That includes pictures, music and movies. The player supports "dozens" of formats, according to Microsoft's Larry Hryb AKA Major Nelson. More formats will be added by the end of the year (including animated GIFs!), as will DLNA network playback.
SmartGlass gains the ability to post updates to your activity feed and read threaded messages. More importantly, SmartGlass can now be used to record gameplay clips. The party system gets some love as well, in particular the ability to require invitations and boot unwanted players. Users with limited internet plans will also be happy to know that the update now allows you to track your bandwidth usage. Perhaps the last noteworthy addition is the ability to have your Xbox One boot directly to TV when turned on.
Check out the video after the break for the full rundown of new features.