KVM is Redhat's virtualization platform of choice, and Fedora supports all of the newest and latest features.
yum -y install kvm virt-manager libvirt python-virtinst
Virtualbox is a great Desktop virtualization package that comes with great guest additions. You do have to compile the kernel modules, so as was posted above, you need kernel-headers, gcc, and alternatively DKMS. From the command line as root, run service vboxdrv setup after getting all the required software installed to build the kernel modules.
VMWare is a good enterprise solution, but I've never appreciated their "free" desktop solutions. Overly complicated for a Desktop user with no virtualization experience.
Overall, I personally suggest KVM if you want to go 100% pure Open Source (which matters to some folk), or VirtualBox if you want to go ease-of-use. Can't run VMs in in each at the same time, kernel modules will clash and potentially crash your system