Denial of Service Attacks

Was just reading this post on CloudPundit - DDoS season regarding several high profile distributed denial of service (DDoS) attacks.

The victims include: The Planet even had Cisco Guard appliance in place.

Makes me wonder what other cloud providers have in place? With the whole world moving to the cloud, what does Amazon and other players have in place to protect our infrastructure from Distributed Denial of Service Attacks (DDos).