It's loooong gone! You'll want to try Carmine's. Two locations: one on Broadway at 90th and the other in the theater district, on W. 44th between 7th-8th Aves. The place is awesome. Much better food than Mama Leone's ever served! The trouble is getting a reservation. And they only serve "family style," that is, each dish feeds six people. So gather a crowd and good luck getting a reservation.
(Curiously, nothing ever moved into the space that used to be Mama Leone's. It's part of the Milford Plaza Hotel (or, as NYers know it, the Mildew Plaza).
If you don't have six hungry people, there are a couple of really good Italian restaurants on Restaurant Row (46th between 8th-9th) -- Becco, Lattanzi, Orso.