No one yet knows whether this is a bizarre guess by the German retailer, a complete mistake, or (possibly) a screw up that revealed Diablo 3 PS3 a little bit early. We're going to have to wait until Sony and/or Activision's press conference to be sure.
The one interesting tidbit about all of this is that the website does not list an Xbox 360 or WiiU version. Which is interesting, because the original Diablo was also PlayStation console exclusive. That could mean that there's some merit to this listing.
Although it could also mean that the retailer is trying to make a prediction, and is using the original Diablo's release plan as a blueprint for how Diablo 3 will go. They'd have to be pretty silly to do that though. Hopefully we'll get more clarification on this during the press conferences this week.