Wordpress 2.5.1

If you download the entire 2.5.1 release, you will be getting over 70 other fixes. 2.5.1 focuses on fixing the most annoying bugs and improving performance.

* Performance improvements for the Dashboard, Write Post, and Edit Comments pages.
* Better performance for those who have many categories
* Media Uploader fixes
* An upgrade to TinyMCE 3.0.7
* Widget Administration fixes
* Various usability improvements
* Layout fixes for IE

Since 2.5 your wp-config.php file allows a new constant called SECRET_KEY which basically is meant to introduce a little permanent randomness into the cryptographic functions used for cookies in WordPress.

via WordPress.org