When George Carlin is asked which HBO concert is his favorite, his answer is always, "Jammin' In New York." The reasons are several: It was his first HBO show done live; it was the first he had done in his hometown, New York City; and it was the largest audience he had ever worked before: 6,500.But Carlin says it also represented a newfound sophistication in his writing. "It was the first time I had done truly extended pieces consisting of separate sections all flowing together. It was a big leap for me."The show, taped at the Paramount Theater in Madison Square Garden and winner of the 1992 CableACE Award, is a perfect blend of biting social commentary and more gently-observed observational pieces.