> One thing, you have to run mkfs on an unmounted partition ( i.e /dev/sdXX
> ). Standard disclamer: I make no claims of responsibility for lost files,
> bla, bla, bla.
 I remembered that I didn't care about a couple of drives so I did it 
regardless of it being blank or not. Yet still I got the same response:

bmike1@bmike1:/mnt$ umount sda6
bmike1@bmike1:/mnt$ ls
cdrom  floppy  hda1  hda5  hda6  hda7  hda8  sda5  sda6
bmike1@bmike1:/mnt$ umount /dev/sda6
umount: /dev/sda6 is not mounted (according to mtab)
bmike1@bmike1:/mnt$ su
Password:
root@bmike1:/mnt# mkfs -t ext2 -j /mnt/sda6
mke2fs 1.34-WIP (21-May-2003)
/mnt/sda6 is not a block special device.
Proceed anyway? (y,n) y
mkfs.ext2: Device size reported to be zero.  Invalid partition specified, or
        partition table wasn't reread after running fdisk, due to
        a modified partition being busy and in use.  You may need to reboot
        to re-read your partition table.

root@bmike1:/mnt# umount sda5
root@bmike1:/mnt# mkfs -t ext2 -j /mnt/sda5
mke2fs 1.34-WIP (21-May-2003)
/mnt/sda5 is not a block special device.
Proceed anyway? (y,n) y
mkfs.ext2: Device size reported to be zero.  Invalid partition specified, or
        partition table wasn't reread after running fdisk, due to
        a modified partition being busy and in use.  You may need to reboot
        to re-read your partition table.

root@bmike1:/mnt#