Just picked this up from the fedora guide and and thought I might put it here for reference.
Suppose you have a .ISO file whose contents you wish to examine or even need to copy some data out of. The fedora-guide suggests the following approach.
mkdir ~/your_disc/ su -c 'mount file.iso ~/your_disc -t iso9660 -o loop'
then to unmount it
su -c 'umount ~/your_disc/'