Whilst there is no integrated capability to perform physical to virtual migrations in RHEV itself, Red Hat provide p2v tools to customers to export existing physical machines to a virtual infrastructure whilst ensuring that relevant changes are made to the new guest like paravirtualization drivers.
RHEV also provides ability to use virt-v2v tool via the manager to migrate workloads from VMWare vSphere in a simple and easy wizard based flow.
RHEV provides the virt-v2v CLI tool as well, enabling you to convert and import virtual machines created on other systems such as Xen, KVM and VMware ESX.