Libraries that have or are contemplating audio tours will be interested in an article appearing on the front page of the Calendar section of today's L.A.Times. The article, For an art tour, press the # key , by Diane Haithman, describes the latest trend in museum audio tours, which is making the tour available via the visitor's cell phone. Museums that are using the technology include the Museum of Contemporary Art and the Japanese American National Museum , both in Los Angeles, and the San Jose Museum of Art . Visitors dial a number on their phones to access the tour, and then enter various codes to hear about particular artworks. The only cost to the user is in cell phone minutes used. Companies providing this technology include Guide by Cell, Inc. , in San Francisco; Museum 411, in Minneapolis; and Spatial Adventures Inc. , in Ashburn, Va.