I just discovered that I can log into my FC1 box as root with either the root password, or by simply leaving the password blank!
Functions this way from a command line, or in a terminal within either KDE or Gnome.
What exactly are you doing to 'log in'?
Is this with 'su' from an existing command line, from the system console, or with a remote access program like ssh, telnet or rlogin?
If possible, see if the behavior is consistant between using su after logging in as a non-root user, logging in on console, or connecting with ssh?
The first place I'd look in this case is in /etc/pam.d/
See if there are any files named *.rpmnew and if so check out the differences between them and the originals. Look especially to see if anything has pam_rootok.so listed, and where.
