It is long overdue and Apple finally fixes the long outstanding Java security holes reported back in August and December 2008 (Ars Technica article).
The Java update is available for Mac OS X 10.4.11 Tiger and Mac OS X 10.5.7 Leopard. Apparently Apple has included the fixes in the Developer Preview version of Mac OS X 10.6 Snow Leopard.
Released on June 15th, 2009:
Java for Mac OS X 10.4, Release 9 | 80.11MB
Java for Mac OS X 10.4, Release 9 delivers improved reliability, security and compatibility for J2SE 5.0 and J2SE 1.4.2 on Mac OS X 10.4.11 and later.
http://support.apple.com/kb/HT3593
http://support.apple.com/kb/HT3633Java for Mac OS X 10.5 Update 4 | 158MB
Java for Mac OS X 10.5 Update 4 delivers improved reliability, security, and compatibility for Java SE 6, J2SE 5.0 and J2SE 1.4.2 on Mac OS X 10.5.7 and later.
http://support.apple.com/kb/HT3581
http://support.apple.com/kb/HT3632
Java for Mac OS X updates are also available through Apple Software Update.