in a 2008 failover cluster running on 2008 R2 and Hyper-V R2, when you create the VM, you designate the preferred owner and the order for which the VM will fail over. For example, VM1 has preferred owners of node1, node2, and node3 listed in the general properties of the VM. VM2 has preferred owners of node3, node2, and node1 listed in that order. If both VMs are located on node1 and it fails, VM1 will fail over to node2 and VM2 will fail over to node3.
In 2008 R2, using cluster shared volumes, each VM acts independently of all others so you can move them without affecting other VMs. You can use quick migration or live migration to move VMs between nodes.