WordPress 3.6 "Oscar" is now out in stable release

From the WordPress blog:

User Features

• The new Twenty Thirteen theme inspired by modern art puts focus on your content with a colorful, single-column design made for media-rich blogging.
• Revamped Revisions save every change and the new interface allows you to scroll easily through changes to see line-by-line who changed what and when.
• Post Locking and Augmented Autosave will especially be a boon to sites where more than a single author is working on a post. Each author now has their own autosave stream, which stores things locally as well as on the server (so much harder to lose something) and there’s an interface for taking over editing of a post, as demonstrated beautifully by our bearded buddies in the video above.
• Built-in HTML5 media player for native audio and video embeds with no reliance on external services.
• The Menu Editor is now much easier to understand and use.

Developer Features

• A new audio/video API gives you access to metadata like ID3 tags.
• You can now choose HTML5 markup for things like comment and search forms, and comment lists.
• Better filters for how revisions work, so you can store a different amount of history for different post types.
• Tons more listed on the Codex, and of course you can always browse the over 700 closed tickets.