Mariah Carey has been tapped to sing the Olympic anthem at the opening ceremonies for the 2004 Olympic Games, to be held August 13 in Athens, Greece. ... Almost all of the Roc-A-Fella family is scheduled to converge on the Pontiac Silverdome near Detroit on Friday for the Roc-A-Fella 4th of July Takeover. Jay-Z, Cam'ron and the Diplomats, Twista and members of State Property are scheduled to perform. Dame Dash, who will also be on hand, says that this is only the beginning of his family's massive gatherings; he's planning a Roc-A-Fella tour in the coming months. ...