A Jetblue Airbus A320-200, registration N625JB performing flight B6-517 from Fort Lauderdale,FL (USA) to Mexico City (Mexico), was enroute at FL300 about 130nm southwest of Fort Lauderdale when the crew decided to return to Fort Lauderdale after a flight attendant received injuries by the service cart. The aircraft landed safely about one hour after departure. The aircraft, that had initially departed with a delay of 2 hours already, remained on the ground for about 3.5 hours, then departed again and reached Mexico City with a total delay of 6.5 hours. The FAA reported erroneously the aircraft involved was N561JB and stated the aircraft returned to Fort Lauderdale "AFTER FLIGHT ATTENDANT WAS INJURED BY CART". The FAA listed the level of injury unknown. The aircraft did not sustain damage.