General

• Featured image previews now support .bmp files
• Featured Image meta box is now hidden for contributors lacking upload capabilities
• New supported oEmbed providers: CollegeHumor, Issuu, Mixcloud, YouTube playlists, TED talks
• Install WordPress in your language
• Streamlined Language management right from the dashboard

Posts

• Display embed previews for audio/visual URLs in Visual editor content box.
• Page scrolling now scrolls post content box.
• Edit Post/Page menu bar sticks to top of content box when scrolling (Visual and Text editor).
• Color picker was re-added to the Visual editor

Media

• Add Media Grid view option (default) for Media Library
• Add “Bulk Select” button to Media Grid view to delete multiple items
• Add oEmbed support for TED talks, Mixcloud, CollegeHumor.com, Issuu
• Expand oEmbed support to include YouTube playlist URLs and Polldaddy’s short URL format
• Remove Viddler oEmbed support
• Update SlideShare oEmbed regex
• Improved media experience on small screen sizes (embedded videos now responsive)
• Native video and audio shortcodes now support Flash playback looping

Comments

• Comments in trash can now be marked as spam.

Plugins

• Display plugins list as grid, with thumbnails, on Add New screen.
• Add popup window with plugin details (displays info from plugin’s directory page).
• Add “Beta Testing” tab to Plugins screen for new features-as-plugins.

Accessibility

• Improved keyboard accessibility in the Add Media panel
• Improved screen-reader support for Customizer sections
• Makes links in help tabs keyboard accessible
• Improvements for screen-readers when managing widgets in the Customizer

Install Process

• Add language select menu as first Installation screen (skipped for localized installs)

Multisite

• mp4 file extension was added to allowed upload file types