I do have a whole chapter on running Hadoop on AWS/EC2. Unfortunately I must admit that I don't go much beyond the scripts included in Hadoop's distribution. The implications of using Hadoop on EC2 is quite subtle, so I devote most of the chapter to clarifying that instead.
As to Tibi's question about dynamically adjusting the size of the cluster, Hadoop is certainly designed to handle it, but I wouldn't recommend doing that with a Hadoop cluster in EC2. Hadoop assumes fairly stable clusters, and slowly "balances" the data across the cluster when you change its size. Just because you can add/remove nodes in EC2 fairly fast doesn't mean that Hadoop can respond equally fast.
You should also keep in mind that Hadoop doesn't necessarily execute just one job at a time. It's optimized for throughput so that if one job doesn't take up all the nodes in a cluster, it will (partially) start the next job in parallel to keep any node from being idle.