Basically, anyone who happens to own a Microsoft account in select regions are able to add music to OneDrive, and to play it back over on Xbox Music. You can also hook up OneDrive with Xbox Music in order to enjoy the playback of your personal music files across your collection of devices. In addition, any music that has been uploaded to OneDrive can be streamed from your collection all the way to the rest of your Xbox Music devices.
Hence, we would not worry too much about the missing release date, since all of the details that have been posted do make it crystal clear that Microsoft is inching closer to a formal launch, and everything does seem to be in place already.