Usage Estimate

You can now view an estimated breakdown of your EC2 usage costs including instances, Elastic IPs, data transfers, EBS provisioning, etc.  The monthly reports are meant to provide a rough estimate of your EC2 usage costs.  Actual AWS billing costs may vary. 

Go to Report -> Usage Estimate and select a monthly report to view.

You will see a breakdown of the various EC2 activities, along with the current billing rate, usage (hours/GB), and costs.