I am uncertain whether Dumpster Drive, the creation of interaction designer Justin Blinder, is actually useful or even meant to be so. It strikes me much more as a sort of digital, networked art project. There might be an interesting thought experiment too around whether the intent and act of removing some digital media affects in anyway the legal analysis over whether the sharing done by the software consists piracy comparable to the activity on more traditional P2P networks.
Dumpster Drive is a file-sharing application that recycles digital files. Using dumpster diving as a model for recirculating unwanted objects, Dumpster Drive allows others to dig through files that you delete on your computer in a passive file-sharing network. Instead of simply erasing data from your computer, the software allows users to extend the lifecycle of their unwanted files and pass them on to others.
The application is only available for Mac. Reading around the site answered my only other question. It does not replace your existing Trash folder at all, rather it provides an additional target. Otherwise I had nightmare images of all kinds of unintentional and embarrassing sharing taking place.