The virtualization concept has been around in some form since 1960s (e.g., in IBM main-frame systems). Since then, the concept has matured considerably and it has been applied to all aspects of computing – memory, storage, processors, software, networks, as well as services that IT offers. It is the combination of the growing needs and the recent advances in the IT architectures and solutions that is now bringing the virtualization to the true commodity level. Virtualization, through its economy of scale, and its ability to offer very advanced and complex IT services at a reasonable cost, is poised to become, along with wireless and highly distributed and pervasive computing de-vices, such as sensors and personal cell-based access devices, the driving technology behind the next waive in IT growth [11]. Not surprisingly, there are dozens of virtualization products, and a number of small and large companies that make them. Some examples in the operating systems and software applications space are VMware1, Xen – an open source