I'm no expert on the options for mounting partitions, but this is how I understand it.
By default, only root can mount a file system (partition). If you use the user option, that means any user can mount the file system, not just root. Once a file system is mounted, I *think* any user can have access to it. However, the access depends on permissions in the file system itself. If the user option is used in fstab, only root and that user can unmount the file system.
If instead of user you put the users option in fstab, any user can mount the drive and any user can unmount the drive. Contrast that with user, where only root and the user who mounted the drive can unmount it. So
user=only root and the user who mounted the drive can unmount it
users=root and *any* user can unmount the drive
In VL6 on all my systems, if the file system on the drive to be mounted is ntfs-3g, only root can mount the drive regardless of whether user or users is in fstab. Once the ntfs-3g drive is mounted, any user can read it and write to it. But for reiserfs or ext3, any user can mount a drive if user is an option in fstab.
I'm usually the only user, so I haven't worried about security on the drives to which users have access. I have a visitor account set up for the rare times someone else will be using my computer. If someone else will be using it, I unmount the other file systems before the visitor logs in. While they could theoretically mount these partitions, they don't know how, wouldn't even think of it, don't know other partitions exist, and have no malicious intent. In a different environment I'd have to find out more about how to make sure nobody could do something I don't want on other mounted file systems.
There is a LOT of very technical and mostly incomprehensible (to me) information on option in
You may want to take a look through it. Also check out