Accoding to AppleInsider, Mac OS X Panther 10.3.9 update is ready for release as soon as this week.

Recent builds, numbered 7W86 and 7W87, provided by Apple to developers, are probably the last seeds for this update of Panther.

The article provides details on the improvements that this update brings :
Mac OS X 10.3.9 will improve boot time for machines with a large number of fonts, while tweaking the performance of Directory Services and FireWire audio. It will also deliver video, USB, fax and modem driver fixes.

Other improvements were already reported in earlier builds :
Mac OS X 10.3.9 will also sport improvements to AFPServer, Bluetooth, Date and Time, DVD Player, FireWire, iDisk Synching, Mail, Networking, Printing, Safari, and Terminal.