Apple has released Mac OS X 10.5.5, the latest upgrade to their Leopard operating system
The Mac OS X 10.5.5 Update is recommended for Mac OS X Leopard versions 10.5, 10.5.1, 10.5.2, 10.5.3 and 10.5.4. It includes general operating system improvements that enhance the stability, compatibility, and security of your Mac.