Mac OS X 10.6.7
Mac OS X 10.6.7 Update is recommended for all users running Mac OS X Snow Leopard.
It includes general operating system fixes that enhance the stability, compatibility, and security of your Mac. In particular, it includes fixes that:
Improve the reliability of Back to My Mac
Resolve an issue when transferring files to certain SMB servers
Address various minor Mac App Store bugs
Full details on the update can be found here and information on the security content of this update can be found here.
Mac OS X 10.6.7 is an essential update for Snow Leopard users.