From Fedora Project Wiki

Serial Console in Fedora 13

The page says To enable the guest console in a Linux fully-virt guest, edit the /etc/grub.conf in the guest and add 'console=ttyS0 console=tty0'. If you add these lines in this order, tty0 will get the primary console and upstart will not start a getty on ttyS0. I would recommend to change the order to tty0, ttyS0.--Faux 08:39, 14 August 2010 (UTC)