Apple released an update to Snow Leopard this week. The update includes important fixes.

The 10.6.2 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 for:

* an issue that might cause your system to logout unexpectedly
* a graphics distortion in Safari Top Sites
* Spotlight search results not showing Exchange contacts
* a problem that prevented authenticating as an administrative user
* issues when using NTFS and WebDAV file servers
* the reliability of menu extras
* an issue with the 4-finger swipe gesture
* an issue that causes Mail to quit unexpectedly when setting up an Exchange server
* Address Book becoming unresponsive when editing
* a problem adding images to contacts in Address Book
* an issue that prevented opening files downloaded from the Internet
* Safari plug-in reliability
* general reliability improvements for iWork, iLife, Aperture, Final Cut Studio, MobileMe, and iDisk
* an issue that caused data to be deleted when using a guest account

For detailed information on this update, please visit this website:http://support.apple.com/kb/HT3874.
For information on the security content of this update, please visit: http://support.apple.com/kb/HT1222.

Apple Also released a security update.

About Security Update 2009-006 Client
Security Update 2009-006 is recommended for all users and improves the security of Mac OS X. Previous security updates have been incorporated into this security update.

Source: Apple.com 10.6.2 Combo Update
Source: Apple.com Security Update Client