Matthew Broderick will introduce playwright Kenneth Lonergan, who will deliver the keynote address at this year's "Curtain Call," the Alliance of Resident Theaters/New York's annual celebration of Off-Broadway. Broderick is currently starring in The Producers on Broadway, while Lonergan's Lobby Hero proved a hit at Playwrights Horizons. The two artists have been friends since childhood. Six "Local Hero Awards" will be presented at the April 23 event, which will be held at the American Airlines Theatre. A.R.T./NY provides a wide variety of financial and practical assistance to the hundreds of small theatre companies which make up its membership.