Here's what AWS has reported about the event (http://status.aws.amazon.com/).
6:33 AM PDT We are investigating increased error rates for API requests in the US-EAST-1 Region.
7:25 AM PDT We continue to investigate the increased latency and errors for the DynamoDB metadata service. The team is rolling out the remaining mitigations that have been developed to mitigate the errors we encountered earlier this week.
9:26 AM PDT Message: We continue to actively work on deploying mitigations to address the increased latencies and error rates for API requests. We have seen improvements in both request latencies and error rates.