[Al_The_Man]

I though you meant PC power supplies as some have done, these linear supplies do NOT usually come with ground connected and it is done at the discretion of the user.
Also I assumed you meant in series, I am not sure I would want to connect this type in parallel, as they each have electronic regulation circuitry, and some have over-voltage crow-bar, This is a SCR placed across the output, and if the voltage goes up by reason of PS defect or large back EMF the SCR fires, placing a high load on the DC output and causes the PS to shut down untill powered down and up again.
Some thing to look out for in Linear supplies of this type.
Al.