On Fedora you have to add a listing into the /etc/fstab file for a USB storage device to be available. Mine says:
/dev/sda1 /mnt/usbdrive vfat noauto,user,users 0 0
Obviously, you have to create the /mnt/usbdrive directory first for it to work.
I read a tutorial on how to do it 'properly', but I haven't gotten around to finding it again...