I have been troubleshooting another issue when I noticed I couldn't mount certain types of CD media from the command line. when I tried:
cat /proc/filesystems
the output returned:

nodev sysfs
nodev rootfs
nodev bdev
nodev proc
nodev cgroup
nodev cpuset
nodev tmpfs
nodev devtmpfs
nodev debugfs
nodev securityfs
nodev sockfs
nodev pipefs
nodev anon_inodefs
nodev inotifyfs
nodev devpts
ext3
ext2
ext4
nodev ramfs
nodev fuse
fuseblk
nodev fusectl
nodev mqueue
nodev binfmt_misc
hfsplus
udf

Shouldn't this report an available iso9660 filesystem?