Prevent a partition on a USB drive auto-mounting in Linux

On Linux (Gnome desktop) how do you prevent one of the partitions on an external USB drive auto-mounting when it attached to the machine?

I don't just want to prevent the Nautilus window from popping up -- I want that partition not to mount.

Fiddling with /etc/fstab is not acceptable, as this is a removable drive that is attached to different machines.

I seem to remember that you create a hidden file in the root of the file system, but I can't remember what it's called. Something like:

touch /media/usbdisk/.no-mount

How do you actually make this work?

To read that file, the partition would have to be mounted. The auto-mounting is a feature of the operating system (actually hotplug, or some other service monitoring USB) and has to be turned off per-machine.

If you're specifically worried about auto-mounting in gnome, and would rather not touch /etc/fstab, try the following command to turn it off for a specific partition:

gnome-mount --write-settings --mount-options noauto --device /dev/sda1

If you no longer want this to happen, erase the settings:

gnome-mount --erase-settings --device /dev/sda1

I also think you can turn off auto-mount altogether through the gconf-editor utililty: desktop > gnome > volume_manager > automount_media

I'm not aware of any way to have the auto-mount daemon look for a file on the drive and unmount the drive on finding it, though I can see the utility in having something like this.