This is not a major release but does included significant improvements to theme customization, custom headers, Twitter embeds, and image captions as well as a host of under the hood improvements.
Live Theme Previews
Try on New Themes
Gone are the days of rushing to update your header, background, and the like as soon as you activate a new theme. You can now customize these options beforeactivating a new theme. Note: this feature is available for installed themes only.
Customize Current Theme
Satisfy your curiosity and try on a fresh coat of paint — you can also use the live preview mode to customize your current theme. Look for the Customize link on the Themes screen.
You can decide for yourself how tall or wide your custom header image should be. From now on, themes will provide a recommended image size for custom headers rather than a fixed requirement. Note: this feature requires theme support.
Choose from Media Library
Tired of re-uploading the same custom header image every time you check out a new theme? Now you can choose header images from your media library for easier customization.
Share Tweets with Style
You can now embed individual tweets in posts. It includes action links that allow readers to reply to, retweet, and favorite the tweet without leaving your site. Just paste a tweet URL on its own line.
This works with URLs from some other sites, too. For more, see the Codex article on Embeds.
Basic HTML support has been added to the caption field in the image uploader. This allows you to add links — great for photo credits or licensing details — and basic formatting such as bold and italicized text.