Won't 'ps aux' show them anyway? I imagine there are some restricted userland tools available for shared hosts to use, but having just checked on a couple of my personal machines, it'll display arguments even for processes started by root.
In the past I've wrapped things in a trivial shell-script to hide their args (and messing with $0 from a perl script can probably be used for fun & games, if desired)
I personally think the UNIX security model is broken for multiuser, so I basically run systems in dedicated security mode (as does ~everyone else; single-user laptop/desktops under OSX or Linux, and servers dedicated to a single user/task/application, or at least VMs dedicated to a single user/task).
UNIX local system security is still nice as a belt-and-suspenders thing, but once someone's on a box, assume they own it. The only exception is some special magic stuff like Hardware Security Modules.
I was appalled when an application - one we paid a lot of money for - did just that by default.
Which is funny because their app sits on top of WebLogic which provides an easy-peasy way of encrypting the passwords. The vendor either doesn't know enough about WLS to make it happen or they don't care.
