Cloud Computing [1, 3] represents a major paradigm shift in computing and information technology strategy. The "Cloud" is a natural evolution of distributed computing and of widespread adoption of the virtualization technology and SOA. In Cloud Computing, IT-related capabilities and resources are provisioned as services, via the Internet and with the essential characteristics such as on-demand, elasticity, metered services, and rapid provision (without requiring possession of detailed knowledge of the underlying technology). The International Journal of Computers and Their Applications (IJCA) has thus scheduled this special issue in response to the fast development and increased application of Cloud Computing.