By now you've certainly seen that Amazon Web Services has achieved PCI Compliance as a Level 1 merchant. This is great; the folks over at Amazon deserve congratulations on joining the cabal of compliant clouds. You've probably also seen the PCI pundits pithily pronouncing, "Just because AWS is PCI compliant, it doesn't mean they make you compliant by using them!". What does this mean?
Put simply, AWS, like Akamai's Dynamic Site Accelerator, is a platform over which your e-commerce flows. It's critically important that that platform is compliant if you're moving cardholder data through it (just as it's also important that PCI compliance is called out in your contract with AWS, per DSS 12.2). But more importantly, the way in which your organization, and your applications, handle credit card data is the key piece of getting compliant. What AWS's certification buys you is the same thing Akamai's does - the ability to exclude those components from your PCI scope.
(if you want to get compliant, the easiest way, of course, is to tokenize cardholder data before it hits your environment, using a service like EdgeTokenization).