I have just taken down the Plone instances for a pending security upgrade. Today at 1500 UTC, a security upgrade is to be published, and without being patched, there are vulnerabilities open. Andreas will take care of the patches in the evening - thanks a lot!
Unfortunately, I am not available constantly during the afternoon, so I have decided to take down the sites, most notably extensions, templates and conference, already 2,5 hours before.
@Andreas: Just ping the website list when you're finished, then I'll take the sites back.
Sorry for any inconveniences this causes.