WordPress Version 3.6 – “Oscar Peterson”
On August 1, 2013, WordPress Version 3.6, named for Oscar Peterson, was released to the public and includes a beautiful new blog-centric theme, bullet-proof autosave and post locking, a revamped revision browser, native support for audio and video embeds, and improved integrations with Spotify, Rdio, and SoundCloud.
For more information on this enhancement and bug-fix release, read the WordPress Blog, the Release Post, and see the Changelog for 3.6. For Version 3.6, the database version (db_version in wp_options) changed to 24448, and the Trac revision was r24973.
Highlights
- New Default Theme – Twenty Thirteen
- Focus on blogging
 - Single column layout with Sidebar / Widgets in the footer
 - Latest Theme Features support, particularly Post Formats
 - Font-based icons (Genericons)
 
 
- Admin Enhancements
- Menus UI improvements
 - Revisions revised to be more dynamic and scalable
 - Autosave and Post Locking
 - Preview Audio and Video on Media Edit Screen
 - In-line login following expired sessions
 
 
- For Developers
- External Libraries have been updated. More Info
 - New audio/video APIs give developers access to powerful media metadata, like ID3 tags.
 - Filters for revisions, allowing you to set the number of revisions ad hoc instead of only via a define. More Info
 - Semantic Markup allows themes to chose improved HTML5 markup for comment forms, search forms, and comment lists.
 - Search content for shortcodes with has_shortcode() and adjust shortcode attributes with a new filter.
 
 
you can read more at Version 3.6 page fromWordPress Codex