The documentary 'Helvetica'[0] featured an interview with Massimo Vignelli. You can watch him talk about typography[1] and how he came to design his iconic 1972 New York City subway map[2].

[0] http://www.imdb.com/title/tt0847817/

[1] http://www.youtube.com/watch?v=El8jDI_ZuiI

[2] http://www.helveticafilm.com/vignellimap.html