Apple has released new versions of Java: Java for Mac OS X 10.6 Update 7, and Java for Mac OS X Lion 2012-002. The new versions include fixes for twelve identified security vulnerabilities; more information is available in this note. These versions correspond to Java Version 6 Update 31, released for other platforms by Oracle in February. (As Mac users probably know, Apple packages and releases its own Java updates.)
If you have Java installed on your system, I recommend that you update to the relevant new version as soon as you conveniently can. You can use the built-in Software Update mechanism, or you can get the new version from the Apple Downloads page.