Thanks for this great help in getting access to my JB device, just thought this little script might help some people who wish to just click an icon to do this work without having to run a command… so this does not require you to create the ~/.bashrc entry
In a terminal

echo ” #!/bin/bash
if mountpoint -q /media/GalaxyS ; then
fusermount -u /media/GalaxyS
else
mtpfs -o allow_other /media/GalaxyS
fi” > MTPattach.sh

Now create a launcher to this file which will mount/umount it