A stormy love story set among Turkish immigrants in Hamburg, Fatih Akin's new movie, "Head-On," has been collecting prizes since its release last year. Yet its true importance may lie elsewhere. As the first ethnic film to be both a box-office and critical success in Germany, it signals new acceptance of multiculturalism. On screen, at least, Germans are now ready to meet immigrants they have long walked past on the street. Alan Riding reports for the New York Times (free subscription required to view).