Actor, director, producer, critically reviled restaurateur, and hotelier Robert De Niro made a cameo appearance before the Landmarks Preservation Commission yesterday to defend the penthouse built atop his new Greenwich Hotel in Tribeca. Some Tribeca residents are urging the commission to force De Niro to tear down the penthouse because its design differs from what was approved four years ago. According to the Times, De Niro pleaded with the commission to retroactively approve the penthouse:......