A. EAL stands for Evaluation Assurance Level, with levels 1 through 7 that are assigned based on completion of Common Criteria security evaluation. Most OSs that support multilevel security achieve EAL 4 level certification; however, it takes time to complete the certification process.
Windows Server 2008 Hyper-V is EAL 4+ certified, as is Windows Server 2008 R2.
Windows Server 2008 R2 Hyper-V will shortly complete its EAL 4+ certification (Windows Server and Hyper-V are currently certified separately). To check which products are certified go to Common Criteria's website.