Welcome to WordPress 3.3
Please update to the latest version!

Using WordPress 3.3 will improve your looks, personality, and web publishing experience. Okay, just the last one, but still.
Version 3.3
What’s New Credits Freedoms
Easier Uploading
File Type Detection

We’ve streamlined things! Instead of needing to click on a specific upload icon based on your file type, now there’s just one. Once your file is uploaded, the appropriate fields will be displayed for entering information based on the file type.
Drag-and-Drop Media Uploader

Adding photos or other files to posts and pages just got easier. Drag files from your desktop and drop them into the uploader. Add one file at a time, or many at once.
More File Formats

We’ve added the rar and 7z file formats to the list of allowed file types in the uploader.
Dashboard Design
Flyout Menus

Speed up navigating the dashboard and reduce repetitive clicking with our new flyout submenus. As you hover over each main menu item in your dashboard navigation, the submenus will magically appear, providing single-click access to any dashboard screen.
Header + Admin Bar = Toolbar

To save space and increase efficiency, we’ve combined the admin bar and the old Dashboard header into one persistent toolbar. Hovering over the toolbar items will reveal submenus when available for quick access.
Responsive Design

Certain dashboard screens have been updated to look better at various sizes, including improved iPad/tablet support.
Help Tabs

The Help tabs located in the upper corner of the dashboard screens below your name have gotten a facelift. Help content is broken into smaller sections for easier access, with links to relevant documentation and the support forums always visible.
Feels Like the First Time
New Feature Pointers

When we add new features, move navigation, or do anything else with the dashboard that might throw you for a loop when you update your WordPress site, we’ll let you know about it with new feature pointers explaining the change.
Post-update Changelog

This screen! From now on when you update WordPress, you’ll be brought to this screen — also accessible any time from the W logo in the corner of the toolbar — to get an overview of what’s changed.
Dashboard Welcome

The dashboard home screen will have a Welcome area that displays when a new WordPress installation is accessed for the first time, prompting the site owner to complete various setup tasks. Once dismissed, this welcome can be accessed via the dashboard home screen options tab.

Content Tools
Better Co-Editing

Have you ever gone to edit a post after someone else has finished with it, only to get an alert that tells you the other person is still editing the post? From now on, you’ll only get that alert if another person is still on the editing screen — no more time lag.
Tumblr Importer

Want to import content from Tumblr to WordPress? No problem! Go to Tools → Import to get the new Tumblr Importer, which maps your Tumblog posts to the matching WordPress post formats. Tip: Choose a theme designed to display post formats to get the greatest benefit from the importer.
Widget Improvements

Changing themes often requires widget re-configuration based on the number and position of sidebars. Now if you change back to a previous theme, the widgets will automatically go back to how you had them arranged in that theme. Note: if you’ve added new widgets since the switch, you’ll need to rescue them from the Inactive Widgets area.
Under the Hood
Flexible Permalinks

You have more freedom when choosing a post permalink structure. Skip the date information or add a category slug without a performance penalty.
Post Slugs: Less Funky

Funky characters in post titles (e.g. curly quotes from a word processor) will no longer result in garbled post slugs.
jQuery and jQuery UI

WordPress now includes the entire jQuery UI stack and the latest version of jQuery: 1.7.1.
is_main_query()

This handy method will tell you if a WP_Query object is the main WordPress query or a secondary query.
WP_Screen API

WordPress has a nice new API for working with admin screens. Create rich screens, add help documentation, adapt to screen contexts, and more.
Editor API Overhaul

The new editor API automatically pulls in all the JS and CSS goodness for the editor. It even supports multiple editors on the same page.