Microsoft haven’t really talked about the media playback features of the Xbox One but Penny Arcade have got some information on the CD and DLNA features. Out of the box the Xbox One will play audio CDs (something the Playstation 4 will not do) and Microsoft are in the process of certifying DNLA playback of the console. So this will mean that you will be able to use it as a Play To receiver and stream content from devices like Windows 7, Windows 8, Android phone or iOS device via apps like Twonky Beam or AllShare
It doesn’t look like you can use is a media server and store you content on the device but there is an Xbox Music Pass subscription option you can go for. None of this is to surprising but it’s good to know, not long to go till we can try it for ourselves.