According to Google an patent for this has been granted to Dirk Zielonka (proprietor of the eponymous "Zielonka Wohnen und Leben GmbH").
According to the patent description the invention doubles as a toilet block, a priest (an implement to clean gutted fish) and is also used in a fishermans knife so you can remove the fish odour from your hands right as you kill the fish.
A German patent application does not mean the thing actually works (personally I still think this is BS), but at least it means the invention has beed inspected by a "Patentassessor" (often an engineer of some description) who decided that it has merits.
It seems nobody else has done an any actual research on this. Wikipedia says that there are no scientific merits to the idea. This seems to be based on linked articles in the NY Times and Wired (that may be have been written by the same stringer from a news agency, since both tell the same anecdote of a chemistry professor who concluded that this doesn't work after washing his hands with it).
As much as it pains me to say, what little evidence there is (i.e. the patent has been granted and the "rebuttals" limit themselves to jokes without research) seems to indicate that there is some merit to the idea that metal bar soap works.