Mac OS X v10.6.6 is now available and addresses the following:

PackageKit
CVE-ID: CVE-2010-4013
Available for: Mac OS X v10.6 through v10.6.5,
Mac OS X Server v10.6 through v10.6.5
Impact: A man-in-the-middle attacker may be able to cause an
unexpected application termination or arbitrary code execution
Description: A format string issue exists in PackageKit's handling
of distribution scripts. A man-in-the-middle attacker may be able to
cause an unexpected application termination or arbitrary code
execution when Software Update checks for new updates. This issue is
addressed through improved validation of distribution scripts. This
issue does not affect systems prior to Mac OS X v10.6. Credit to
Aaron Sigel of vtty.com for reporting this issue.

Mac OS X Server v10.6.6 may be obtained from the Software Update
pane in System Preferences, or Apple's Software Downloads web site:
http://www.apple.com/support/downloads/

Information will also be posted to the Apple Security Updates
web site: http://support.apple.com/kb/HT1222

Thanks go out Dave who noticed the apple security update information to OS X v10.6 through v10.6.5 which was blank earlier today.