This is a more widespread EC2/EBS issue: http://status.aws.amazon.com/
"8:50 PM PDT We are investigating degraded performance for some volumes in a single AZ in the us-east-1 region."
AWS has been historically bad at reporting the severity of their outages promptly.
AWS is a fascinating science experiment. Pity about the websites, though.
God only knows what they reserve the red circle for...