"New Socialist Things" (新生事物, Xinsheng shiwu) was a concept developed by the Gang of Four, most probably by its theoretician Yao Wenyuan. Its meaning seems to have been kept deliberately vague, and could embrace at any given time such diverse elements as the yangbanxi, the revolutionary model works espoused by Jiang Qing; the barefoot doctors that were sent to the countryside to provide health care for all; the May Seven Cadre Schools, where intellectuals, officials and various functionaries were reeducated; the setting up of the revolutionary committees in all institutions and at all levels; the ‘Up to the mountains, down to the villages’-campaign that set out to turn the former Red Guards into peasants; and even the Cultural Revolution itself.
In short, as Helmut Martin indicates, the concept functioned as a kind of open bank account, in which the radical faction could deposit everything it considered as an achievement. Defending the "new socialist things" itself became a battle cry during the succession struggle between the Gang and Hua Guofeng in September 1976.
Helmut Martin, Cult & Canon - The Origins and Development of State Maoism (Armonk, NY, etc.: M.E. Sharpe Inc., 1982)