WordPress 2.8.5 is an update to 2.8.4 with the following changes

• A fix for the Trackback Denial-of-Service attack that is currently being seen.
• Removal of areas within the code where php code in variables was evaluated.
• Switched the file upload functionality to be whitelisted for all users including Admins.
• Two importers of Tag data from old plugins have been removed

You can read more about the changes and get yourself a Copy of WordPress ( WordPress is FREE ) from the WordPress Website

One of the really great features I’ve only just discovered is you can now update your wordpress blogs within your sites Dashboard. (Apparently this feature has been available for the last 6 months.)