One thing I'm completely ignorant of is how to people from countries where non-latin alphabets are write code? Eg if you're Chinese, Arabic even Russian do you have to do everything in English and English characters? I'd hope there is a Unicode mapping into other characters - is there any language that supports this? Even for libraries would be nice.
Personally I prefer it when they use English obviously (I don't speak German), but it also means you don't get ridiculously long identifiers.