Microsoft's PR & Event Manager Lidia Pitzalis confirms that only US, UK, Mexico, Japan, and Canada will have Xbox 360 Kinect's "voice control" feature enabled at launch. Voice controls for French Canadians, however, will arrive in the Spring 2011 update. Germany, Italy, France, and Spain will receive the feature in Spring 2011.
Microsoft says that the problem isn't just with languages, but also with dialects of those languages. Microsoft claims that they even had to create different software versions for the US and UK – even attending to the range of dialects in those two countries was probably a massive feat (the British Library has a good database of accents for those of you that disagree).