I don't know why it would be commented out.
you can also fix the ownership of files using "uid=xxx,gid=xxx", so you could make all files owned by zaurus (get the uid/userid from /etc/passwd and the gid from /etc/group).
this is particularly useful when, say, mounting a windows share on a linux box. here's one of my fstab entries
//192.168.1.2/download /mnt/mypc/download smbfs noauto,users,username=paul,uid=1000,gid=users 0 0
the username option tells smb to login with that username, otherwise it would try to use root.