"The 10.6.8 update is recommended for all users running Mac OS X Snow Leopard and includes general operating system fixes that enhance the stability, compatibility, and security of your Mac, including fixes that:
• Enhance the Mac App Store to get your Mac ready to upgrade to Mac OS X Lion
• Resolve an issue that may cause Preview to unexpectedly quit
• Improve support for IPv6
• Improve VPN reliability
• Identify and remove known variants of Mac Defender
For detailed information on this update, please visit this website: http://support.apple.com/kb/HT4561.
For information on the security content of this update, please visit: http://support.apple.com/kb/HT1222."