Windows Server 2008, formerly code-named Longhorn, is finally out in the wild. The new version delivers enhancements in virtualization, manageability, and security that will entice firms to the new edition — but Microsoft's server virtualization solution, Hyper-V (code-named Viridian), is undoubtedly the most important enhancement. Windows Server 2008 retains a similar licensing structure to Windows Server 2003, but trends in virtualization and consolidation will have a significant impact on which licenses you purchase.