The first beta version of WordPress 3.9 is now available for testing. Full release of the software is set for April 15, (of all days!).
So what can we expect from version 3.9?
Cleaner markup. Also try the new paste handling — if you paste in a block of text from Microsoft Word, for example, it will no longer come out terrible. (The “Paste from Word” button you probably never noticed has been removed.)
Updated TinyMCE, the software powering the visual editor, some plugins that added stuff to the visual editor (like a new toolbar button) no longer work,
added widget management to live previews (the customizer).
WP brought 3.8′s beautiful new theme browsing experience to the theme installer
Galleries now receive a live preview in the editor.
You can now drag-and-drop images directly onto the editor to upload them
New audio/video playlists.