Under the 9.0 RC1 (and all 9.0 betas and even 8.2), if supermount is loaded, you cannot format a floppy disk. The work around is to disable supermount, unmount and then remount the floppy and format it. Then after the format, unmount it and enable supermount again.
Although many people no longer use floppy disks, since Mandrake is directed at the desktop and newer user, it would be great if this could be fixed (or at least not have a format option in KDE/Gnome for the floppy device). Joe Braddock