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.
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 at /Applications/Utilities/Java/J2SE 5.0/.
Software developers may visit the Java Reference Library for information on this release's features.