Ubuntu 8.10 released [an upgrade], which can be downloaded via the [list of mirrors]. If you ever want to mount an iso as a drive, use the command:
sudo mount -o loop ubuntu-8.10-desktop-i386.iso /media/cdrom2
sudo mount -o loop ubuntu-8.10-alternate-i386.iso /media/cdrom3
If you always want the ISOs available you can modify your [fstab].