Automatically mount CD when inserted is checked in GNOME Control Center->Peripherals->CD Properties. When I insert a data CD, it automounts just fine. The command fuser -m /cdrom returns that /cdrom is in use by the GNOME file manager. I close the file manager, and fuser -m /cdrom returns no uses of that directory. As soon as I eject the CDROM, the message "VFS: busy inodes on changed media." appears in the current VC and in /var/log/messages. There are no files listed in /cdrom, but the mount command returns that /cdrom is still mounted. After I issue the command umount /cdrom, the messages disappear. If I do not issue the umount /cdrom command, the messages do not go away.
You are not supposed to remove mounted media. The fact that no process is using an inode doesnt mean it isnt cached.