There was this “in what kind of threads will you always find certain Dopers?”-thread in MPSIMS or IMHO…
Well, if you open a thread on interpreting and languages - just wait till universe.zip comes along… 
The general rule of the AIIC and other professional associations, as well as of the international organizations (UN, EU, OSCE etc.) who employ interpreters on a regular basis, is that interpreters should work into their native language. That said, most interpreters have “active” and “passive” languages (called B and C languages - A is the native language, normally active) - they are able to interpret into and from their active language(s) and from their passive language(s) to their A-language. When working at conferences etc. this is usually required, because employing two interpreters (you need to take turns every 20-30 minutes) for every language pair and direction is very expensive. Also, for conversations or negotiations it is impractical to use two interpreters - so when two heads of state talk behind closed doors, there is usually only one interpreter in there workig both ways (unless they don´t trust each other…).
While the EU guidelines say people should only interpret into their native language, they have had to make exceptions for the “exotic”, i.e. not so wide-spread, languages such as Greek or Finnish. There just aren´t many French/ English/ Spanish/ Portuguese natives around who are fluent in Finnish, so in these cases, Finnish interpreters work into their B-language as a transition phase solution (which they are hoping to overcome soon, but it´s only going to get more complicated when Estonian, Lithuanian and other fun languages come along with the EU enlargement…). That is then used as a pivot language for the other booths - e.g. Finnish to English, and the other interpreters listen to that booth and interpret from English into their respective languages.
Not an ideal solution, but sometimes necessary.
And you are all absolutely right - of course the results are better when your target language is your native tongue. The other way round, you may be able to render a correct translation, but it will not be as idiomatic (and therefore natural) as it could be.
In difficult cases it does have its advantages to be a native speaker of the source language, though. If the speaker uses extremely idiomatic expressions all the time or keeps referring to events or places few foreigners (even interpreters who keep themselves informed as a rule) would know about (even worse: making a reference to a typical children´s book almost every English speaker knows but most others don´t - imagine you´re at a physics conference and some witty speaker compares something to the Cat in the Hat… these things happen!), loads of quotes or extremely metaphorical language, it can be almost impossible for a non-native to even fully grasp what is being said in the few seconds available (you just don´t have the time to ponder the meaning and find an equivalent, you have to react quickly, and if you´ve got no idea what the speaker is getting at, you´re lost). A native speaker, however, has the benefit of fully understanding the source text and can make an intelligible, correct translation. It may be not as colourful and idiomatic as the original, but this is one of the rare cases where an interpreter working into a foreign language can sometimes do a better job than the guy interpreting into his mother tongue.
But most interpreters are very good in their B-language, so it is perfectly ok for them to work into that language, and, as pointed out, it is often necessary for “smaller” languages.
As for news broadcasts - that depends. Is it actually a live interpretation or is it a translation dubbed on later? (It´s easy to tell the difference - an interpretation is never absolutely fluent, it will have pauses, hesitations and the occasional slip of grammar; few interpreters can deliver an absolutely perfect speech that sounds as if it were the original, at a consistent speed and with that news-speaker tone of voice.)
This is a cost question, of course. If the speech isn´t live, they often make a written translation and then someone, maybe a foreign correspondent who isn´t from the US, makes the voice-over. And even if it´s live, it´s normally cheaper to employ someone local than fly in an interpreter from the US (or wherever).
I´ve never heard of anyone intentionally employing someone with an accent to stress the fact that the original speaker is a foreigner (or “to add local colour”, to put it more nicely). But I won´t say it´s not true, and I wouldn´t be surprised if what ppeterson says is true - it certainly would be a very powerful opinion-shaping instrument.
:shudder: That would be totally against any self-respecting interpreter´s code of ethics.
You can do that in a film, but when you´re interpreting real people in real life, you´re there to convey the original message.
Not the words, but the content. The audience knows the guy speaks another language, that´s why they hired you!
Absolutely inacceptable, from my point of view.
Phew, this was long. But don´t I just love my job… 