If you haven’t been automatically notified from your Mac’s Software Update, you might want to look at this. It’s a security update, “Java for Mac OS X v.10.5, update 4.” Several news sources on Google reported it. I looked at http://www.appleinsider.com/articles/09/06/15/apple_plugs_critical_java_security_hole_affecting_tiger_leopard.html
Sure enough, it came up when I looked at Software Update on my Mac. It said, "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. This release updates Java SE 6 to version 1.6.0_13, J2SE 5.0 to version 1.5.0_19, and J2SE 1.4.2 to 1.4.2_21.
Please quit all web browsers before installing this update.
For more details on this update, please visit this website: http://support.apple.com/kb/HT3581
Check it out for yourself. "Secure" is such a nice concept.