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.
Code freezes for coming WordPress 3.8 update.
WordPress 3.8 is expected to be out of Beta and available for production sites.