Andrew Nacin Announced WordPress 3.9 Beta 1 is now available (Playlists like Galleries, Drag and Drop Photos to Editor, Updated TinyMCE, Live Preview Addition for Galleries, Widget Live Previews, Paste from Word to Post): There is a good sized test list of items. Get the Beta Tester plugin to help test on non-production sites:
The release includes playlist support, drag and drop photos to editor, TinyMCE upgrades and quite a bit more. Read the Official WordPress 3.9 Beta 1 Announcement Here
Playlist function allows for playlists to be organized like galleries for audio and video files.