$ VBoxManage -nologo list vms
WARNING: The vboxdrv kernel module is not loaded. Either there is no module
         available for the current kernel (2.6.25.11-60.fc8) or it failed to
         load. Please recompile the kernel module and install it by

           sudo /etc/init.d/vboxdrv setup

         You will not be able to start VMs until this problem is fixed.
...
$ su -
# cd /etc/init.d
# ./vboxdrv setup
Stopping VirtualBox kernel module                          [  OK  ]
Recompiling VirtualBox kernel module                       [  OK  ]
Starting VirtualBox kernel module                          [  OK  ]
# ./vboxnet status
VirtualBox host networking is loaded.
# ^D
$ VBoxHeadless -startvm fedora9