Slate: “Since the beginning of Hollywood, filmmakers after an exotic or romantic effect have taken their stories abroad. Since the advent of sound in the late 1920s, this tendency has created a little-discussed problem: How to represent foreign speech? Many filmmakers are content to shoot against a painted backdrop, toss in a few bonjours, and call it France, while others go to great lengths to have characters look and speak as authentically as possible. There are no hard and fast rules, but it’s a tricky business—directors must balance the expectations of realism with ease of viewing. They want dialogue to be convincing, but they don’t want to alienate their audiences with accents or subtitles that aren’t essential to the story.
We tend to take language for granted; how foreign speech is handled in film shapes our experience as viewers, usually without our knowing it. The accompanying slide show explores the various ways that filmmakers negotiate foreign speech, highlighting those films that approach the problem as an opportunity to deepen the story.
Click here for a video slide show on foreign speech in Hollywood movies.”
Translabor 
Interesting. Good analysis of the variety of ways a foreign language may be presented in films. One that I think might be added to the list is something that I have seen in a number of silent films. Text, usually a letter, is shown in the original foreign language, but then there is a dissolve to an English translation.
The most annoying translation I have seen in a film lately happened while watching Heartbeat (1946), with Ginger Rogers, Basil Rathbone, and Jean Pierre Aumont. It basically has everybody speaking the King’s English although set in Paris. Then Jean Pierre Aumont comes along, a real Frenchman, speaking English with a thick French accent. For some reason I was willing to go along with the idea that all French people spoke English, but the mixing of a French accented person just went too far to allow me to continue my suspension of disbelief.