On the 6th of November a patch will be released to the community for a number of vulnerabilities in Plone.
Due to the severity of the vulnerabilities, we recommend anyone maintaining their own Plone site to *shut it down completely* before the patch is released and keep it down until the patch has been installed and verified to work.
There will be downtime in this period for customers who have deals for security updates.
More info about the vulnerabilities is available here:
http://plone.org/products/plone/security/advisories/20120830