While this site is actually operating on WordPress 3.7 alpha, WordPress 3.6 is officially available for download and update via the WordPress admin panel.
… 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.
The best change for sites using multiple authors is the post locking and revisions control. It’s now possible to see who made changes to a post – line by line.
Something I have not tried yet is the Built-in HTML5 media player for native audio and video embeds with no reliance on external services. I hope to attempt this in my personal blog this evening.
Not everything is complete. The Codex pages still need work. For example, the functions added into WordPress 3.6 have pages but lack information.