One of the options offered when you right click the desktop or within a Nautilus window is "wipe available diskspace." I'd think that means all unused diskspace but assumptions can be dangerous. I don't want to try it only to find out that available meant "all". I can't remember seeing this option before 12.04.

I was asked to provide an image but unfortunately when right clicking to get the drop down menu, the print screen function doesn't respond thereby making an image impossible.

It appears that no responder so far has actually used this nautilus option. Jorge suggested that the feature was actually nautilus-wipe and I verified that is the case by removing nautilus-wipe and seeing that the menu option is now gone. Documentation for nautilus-wipe is almost non-existent and what little I found was superficial and contradictory. This doesn't leave me with a warm and fuzzy feeling regarding my using an application or feature that purports to "wipe disk" without a clear definition of what is wiped.