passwords not recognized when su'ing from a terminal

[Andy Green]

Somebody in the thread at some point said:
> I have F7 (fresh install in late June) on a Dell Latitude D610.
> 
> Just a few days ago, I stopped being able to 'su' or 'su some_user'
> from a terminal: the passwords are no longer accepted.  Same problem
> to unlock a session (need to enter the password).

Is su still suid root?

# ls -l /bin/su
-rwsr-xr-x 1 root root 27052 2007-04-02 16:33 /bin/su

-Andy