WordPress 2.5.1 Available, Upgrade!
First update for WordPress 2.5 branch has been released. WordPress 2.5.1 contains performance improvements along with critical security fixes for vulnerabilities which are not public yet. Totally, WP 2.5.1 contains over 70 bug fixes.
If you are using WordPress Automatic Upgrade Plugin, then upgrading shouldn’t be a problem. For others, (as always) I have put together an express upgrade zip, which contains only files that have been modified subsequent to WP 2.5. You may download it from here [411 KB].
Likewise, if you are only concerned about security fixes, you need to upgrade just 3 files (wp-includes/pluggable.php, wp-admin/includes/media.php, and wp-admin/media.php).
Just keep in mind that you need to be running WP 2.5 to do an express upgrade to WP 2.5.1, else you’ll need to download the whole WP 2.5.1 package for here and then perform the upgrade. More details on the upgrading are available in Codex.