VMware Server is a robust yet easy to use product for users new to server virtualization technology. VMware Server enables companies to partition a physical server into multiple virtual machines, and to start experiencing the benefits of virtualization.You can download it here.
“Offering VMware Server for free will bring VMware's proven virtualization technology to a wider audience, allowing companies to achieve the benefits of virtualization, such as cost reductions and flexible server provisioning.”
VMware Server Beta free download

VMware Server beta can now be downloaded for free: