Updates in this new release include:
- WordPress Widgets allow you to easily rearrange and customize areas of your weblog (usually sidebars) with drag-and-drop simplicity
- Full Atom support, including updating our Atom feeds to use the 1.0 standard spec
- A new Blogger importer that is able to handle the latest version of Google's Blogger product
- Infinite comment stream, meaning that on your Edit Comments page when you delete or spam a comment using the AJAX links under each comment
There's also lots of developer features including a new set of WordPress-specific XML-RPC API, the use of jQuery for a number of internal functions and the internal mail functions now use phpMailer. Check out the official release announcement for more details or just head over and download your copy today.
UPDATE: Pufone.org also has a guide to upgrading from your current version, complete with screenshots to show the way.