In Czech Republic, the debate is still somewhat alive between three schools of thought:
- Use English, only 10^7 people speak Czech
- Use Czech without diacritical marks, not every environment supports them
- Use Czech with diacritics, yay Unicode!
Since that time I worked in a Dutch company which had most code written under the assumption that "we're all Dutch here, what would we use English for?" (and later expanded across Europe), I've switched to English for everything - code, comments, and metadata. After all, my colleagues have been Czech, Dutch, Bulgarian, French, American, Turkish, Swedish, and Croatian - with English being the common language (after all, the Dutch guy was not happy when we needed him to translate comments every day ;)).