Apple has now released Security Update for Mac OS X 10.6 Snow Leopard and OS X 10.5 Leopard. Apple recommends this update as it fixes previous known security issues. Security Update 2011-002 for Snow Leopard is only 4.43MB and requires Mac OS X 10.6.7. However for Leopard, is at 241.35MB and requires Mac OS X 10.5.8. This can be downloaded directly from Apple's website or via the Software Update utility.