29 of 29Image
An instance's state will change to terminated once it has been fully shut down and de-provisioned. From this point on, you won't be billed.
You can repeat this entire procedure any time you want to do some Hadoop work. EMR clusters are available on-demand and you can shut them down as soon as you're done using them.
For a more permanent cloud-based cluster, you can provision raw EC2 instances, installing Hadoop on them yourself and federating them into a cluster.
Cloud-based, on-demand Hadoop cluster services comparable to AWS EMR will soon be avaiable from Microsoft, Google and Rackspace, leaving fodder for future galleries here on ZDNet.