Hyper-V R2 ships free with Windows Server 2008 R2, although to take full advantage of some of its more advanced capabilities customers will have to purchase System Center Virtual Machine Manager, which costs US$869 per physical server.
The new features include Live Migration, which allows virtual machines to be moved from one physical server to another without interrupting service. Hyper-V R2 can also take advantage of more powerful servers, with support for up to 64 physical processors, and allows virtual machines to be migrated between two servers based on the same processor family, such as AMD's Opteron chips.