The new Apple MacBook Pro’s come with both J2SE 1.4 and J2SE 5.0. J2SE 1.4 is set as the default. If you want to make J2SE 5.0 the default JVM, open up a terminal and type the following:
sudo mv CurrentJDK CurrentJDK.previousVersion
sudo ln -s 1.5 CurrentJDK
Update 6 of the JDK is now available for downloading from http://java.sun.com. for Windows, Linux and Solaris.
The current release is now 1.5.0_06.
Release notes are available here.
J2SE 5.0 Update 5 is now available from here.
A list of changes can be found in the release notes.
JDK 5.0 Update 4 is now available for download from java.sun.com.
The list of changes made to this version can be found here.