Apple has just released Mac OS X v10.4.11 and Security Update 2007-008 which fix a long list of security vulnerabilities. If you are running Mac OS X 10.4 (Tiger) I recommend updating your system as soon as possible.
Also, Apple has released an update for it's Safari for Windows BETA. See my previous Safari for Windows posting for my thoughts on using beta software.
For more information, see Apple Security Updates.