The latest and greatest version of the WordPress software — 3.3, named “Sonny” in honor of the great jazz saxophonist Sonny Stitt — is immediately available for download or update inside your WordPress dashboard.
WordPress has had over 65 million downloads since version 3.0 was released, and in this third major iteration the WordPress team have added significant polish around the new user experience, navigation, uploading, and imports.
Experienced users will appreciate the new drag-and-drop uploader, hover menus for the navigation, the new toolbar, improved co-editing support, and the new Tumblr importer. We’ve also been thinking a ton about what the WordPress experience is like for people completely new to the software. Version 3.3 has significant improvements there with pointer tips for new features included in each update, a friendly welcome message for first-time users, and revamped help tabs throughout the interface. Finally we’ve improved the dashboard experience on the iPad and other tablets with better touch support.
There is a ton of candy for developers as well. I’d recommend starting your exploration with the new editor API, new jQuery version, better ways to hook into the help screens, more performant post-slug-only permalinks, and of course the entire list of improvements on the Codex and in Trac.