The Virtual Machine Manager application (virt-manager) is a desktop user interface for managing virtual machines.
The kernelnewbies website has a considerable amount of information on Linux virtualization.
Another good option for a virtualization server is CentOS. Nixcraft has a very good article about setting up a CentOS KVM virtualization server. They are using CentOS v5.3.
There is a great Startup guide for KVM with CentOS on ITSC blog. But this time it is the later CentOS 6.0 version and they are setting up a headless server. They add virt-manager to the headless server and run it remotely from a seperate management host–very useful.