The new 6-core AMD Opteron processor (codenamed ‘Istanbul’) will provide a total of 24 logical processors (cores) on a 4-socket system and 48 logical processors (cores) on an 8-socket system. In a non-virtualized IT environment, there aren’t many apps/services that are designed to utilize these large system resources. However, with Hyper-V in Windows Server 2008 R2, it’s a natural fit. Windows Server 2008 R2 Hyper-V provides support for these new processors allowing large resources to be used to consolidate potentially hundreds of virtual machines on a single host.
More info: Windows Virtualization Blog