According to the Apple website Java6 has finally been released for Mac OSX 10.5. No further details were given about support for other operating systems.
"About Java for Mac OS X 10.5 Release 1
This Java for Mac OS X 10.5 Update 1 adds Java SE 6 version 1.6.0_05 to your Mac. This update does not replace the existing installation of J2SE 5.0 or change the default version of Java.
This update provides Java SE 6 version 1.6.0_05.
This release does not change the default version of Java. This release is only for Mac OS X v10.5.2 and later, and should not be installed on earlier versions of Mac OS X. This release is for 64-bit Intel-based Macs only and cannot run on PowerPC-based or 32-bit Intel-based Macs.
Software developers can visit the Java Reference Library for information on this release's features."