In just the past few hours Apple made Java for Mac OS X 10.5 Update 3 available to the public. In Apple’s own words:
This release updates the Java Web Start and Java Applet components to address security and compatibility issues. This release supports all Intel-based and PowerPC-based Macs and requires that Java for Mac OS X 10.5 Update 2 be already installed.
The update is just 3 MB and does not require a reboot. Enjoy, Alex.