Version 2.5.1 of WordPress is now available. It includes a number of bug fixes, performance enhancements, and one very important security fix. We recommend everyone update immediately, particularly if your blog has open registration. The vulnerability is not public but it will be shortly.
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.
For more information about the update please visit http://wordpress.org/development/ .