Just got an e-mail from them:
Unfortunately backups for your container from our master backup repository are not available. If you utilized our free Central Backup feature to create a restore point for your service we can restore from that backup. If you did not utilize that free service we do not have backups and will be unable to restore any of your data.
So... yep, that's it. All my sites are gone. Mea maxima culpa.
This was the most UN-slick deal ever for me.