VirtualBox is a popular Virtualization product for Windows, Linux, Mac & Solaris. They have a RPM repository set up so people can alway get the latest version of it.

To install, first become root, and then download the repo file and save it in /etc/yum/repos.d.

wget http://download.virtualbox.org/virtualbox/rpm/fedora/virtualbox.repo -O /etc/yum.repos.d/virtualbox.repo

Then install the dkms package to make sure your kernel gets host kernel modules each time the kernel is updated.

yum install dkms.noarch

Finally, install VirtualBox 4.0:

yum install VirtualBox-4.0