Cloud computing has the potential to become a major tool for scientists and engineers to access high performance computing resources. In fact, it is becoming an important tool that enables efficient high performance computing while reducing the associated cost of building dedicated high performance computing systems. New developments are driving the evolution of computing resources across many application segments. In this paper we demonstrate the concept of High Performance Computing in a cloud and show that HPC clouds can deliver the needed utilization and scalability on par with the current native HPC approach of designing dedicated systems for specific applications.