I started seeing posts about this on FB last night.  The Summit was stalled in NY harbor after pushing off from her moorings. Unfortunately, it appears that engineering opted to return to the dock because of the technical issue that was discovered.
It is not clear if people are disembarking or if Celebrity is going to try and repair and depart again. In any event, I really feel for the passengers. It is very disappointing indeed... especially in light of the fact that this is not the ship's first problem with the propulsion system.