Google Docs code includes references to some upcoming features that could make the service better suited for storing media content. There are many references to a preview pane that will allow you to view more information about your files and even check the content without actually opening the files.
There's even a player for audio files, much like the video player launched last week. The preview pane will probably allow you to play music files from the Google Docs homepage.
You'll also be able to create playlists (here's the icon for playlists):
Another new option lets you group files from multiple folders in collections.
At the moment, Google Docs includes a small list of applications, but that will change when you'll be able to add third-party apps. That's why Google will have to add a new option for selecting the application that will open a certain file.
It's likely that some of these features will be available in the new Google Docs interface that has been accidentally revealed in a YouTube video.