From Fedora 14 , its not allowed to login using tty.
Neither root nor other users can login using tty.
This problem is caused by a file in /etc/udev/rules.d/
So i deleted all the files in that folder.
Dont worry, it wont do any harm, I tested it in my F15
reboot the system
Now you can login using tty.
Some of the deleted files are automatically created after the reboot