I just got an email from Netflix:
Our shipping system is unexpectedly down. We received a DVD back from you and should have shipped you a DVD, but likely we have not. […]
We are sorry for any inconvenience this has caused. If your DVD shipment is delayed, we will be issuing a credit to your account in the next few days. You don’t need to do anything. The credit will be automatically applied to your next billing statement.
Again, we apologize for the delay and thank you for your understanding. If you need further assistance, please call us at 1-888-638-3549.
– The Netflix Team
Their website has the following message:
That explains why I haven’t gotten any movies this week.