Apple has released new versions of the Java run-time software for Mac OS X. As Mac users probably know, Apple packages and releases its own Java updates, which means there is typically a delay between the availability of a new version (for Windows, Linux and UNIX) from Oracle, and the release of Apple’s version. This new release from Apple corresponds to Java version 6 update 24, released by Oracle on February 17. That release fixed a number of security vulnerabilities.
Apple has two updated versions available: Java for Mac OS X 10.6 Update 4 and Java for Mac OS X 10.5 Update 9. (Why Apple insists on assigning its own update numbers, rather than using the “official” Oracle numbering, is beyond my grasp.) Details of the security fixes are given in the “Security Content” pages for Mac OS X 10.6 and Mac OS X 10.5.
I recommend installing this update as soon as you conveniently can.