Red Hat is offering a 60 day trial installation of RHEV 3. RHEV is an enterprise virtualization product based on RHEL and KVM. You can read more about it at Wikipedia and on Red Hat’s own product page.
The benefits of RHEV and KVM are strongest for Linux virtualization needs. Red Hat focused on building up KVM, with RHEV, to a product that can provide fast and stable Linux virtualization on the server and desktop.