Apple today released Java 2 Platform Standard Edition (J2SE) 5.0 Release 3 which includes version 1.5.0_05 and improves functionality of J2SE 5.0 on Mac OS X v 10.4 Tiger 10.4.2 and later. This release does not replace the existing installation of J2SE 1.4.2.
Java 2 Platform, Standard Edition (J2SE) 5.0 Release 3 allows applications and applets developed for the J2SE 5.0 platform to run on Mac OS X v 10.4.2 and later. It is available via Software Update or as a standalone installer.
This update does not change the default version of Java on your Mac from Java 1.4.2 to J2SE 5.0, though Java applications that require J2SE 5.0 may specifically request it. You can change the preferred Java version for applications and applets by using the new Java Preferences utility. This utility is installed by the J2SE 5.0 update here: /Applications/Utilities/Java/J2SE 5.0/
Installing J2SE 5.0 Release 3
1. Get the J2SE 5.0 Update here.
2. Double-click the “J2SE50Release3.dmg” disk image file that you downloaded, and it will mount to appear as a disk in the Finder.
3. Open the mounted disk, then double-click the Installer icon.
4. Follow the onscreen instructions to complete the installation.
More info and download link (42MB) here.