In a Google+ hangout for English and Hindi speaking folks this week, a Googler said that it is best to have your URLs to be in the same language as your content.
He said, "It is better if you have your URLs in the same language as your content."
This obviously comes into play for web sites that are in non-English languages that sometimes use an English URL structure. Google is saying it is better to use the language format in your URLs that your content is in. It is not required, but it is better.
He said this at the 47:34 mark into the video, here is the embed:
Forum discussion at Google+.