From LQWiki

VirtualBox is easy-to-use virtualization software. Originally developed by innotek, VirtualBox was released as Open Source in January 2007. VirtualBox is available in two versions: The Open Source Edition (OSE) (released under GPL) and the full binary package (licensed under Virtualbox Personal Use and Evaluation License (PUEL)).

SUSE Linux

• install it

yast -i virtualbox-ose

• load its kernel module

modprobe vboxdrv

• start it

VirtualBox

Fedora11 Linux

• install it

yum install dkms
yum groupinstall ‘Development Tools’  
yum groupinstall ‘Development Libraries’ 
yum install SDL kernel-devel kernel-headers 

• load its kernel module

/etc/init.d/vboxdrv setup
modprobe vboxdrv

• start it

VirtualBox

Website

http://www.virtualbox.org/