WordPress 2.8.5 has been released, and is now available for download.  This release has been dubbed a security”hardening” release, meaning there have been proactive measures taken to further secure WordPress, and to prepare for the future release of WordPress 2.9.
From the official WordPress Blog:
As you know over the past couple of months we have been working on the new features for WordPress 2.9. We have also been working on trying to make WordPress as secure as possible and during this process we have identified a number of security hardening changes that we thought were worth back-porting to the 2.8 branch so as to get these improvements out there and make all your sites as secure as possible.
The headline changes in this release are:
We recommend that you upgrade your site to this new version of WordPress to ensure that you have the best available security protection.
To upgrade, you can use the upgrade feature built into the WordPress admin panel, or contact us if you require further assistance.
Saw this update Yesterday and the first thing which I did
Replywas Backup my Db and updated the wordpress. Though wordpress are releasing very quick update..