Apple has just released Mac OS X Panther 10.3.9 update for the Standard and Server versions. The update weights 51.3MB and is available through the Software Update utility.

Here are the notes that Apple provides with the update :

The 10.3.9 Update delivers overall improved compatibility and reliability for Mac OS X v10.3 "Panther" and is recommended for all users.

Improvements include:
file sharing and directory services reliability for mixed Mac and PC networks
Mail, Safari and Stickies application reliability
compatibility for third party applications and devices
previous standalone security updates

Apple provides additional information on this update on this page [1]. More information on Mac OS X Server update is available here [2].