Microsoft did this very extensively. Many Non-English versions of Excel do save CSV-files with a semicolon as a separator and it probably was handled differently too in normal Excel files.
But it goes even further, it affected their scripting languages even to this day with newer languages like their BI script (forgot the name of the language). For example, parameters of function calls aren't separated by ',' anymore and ';' is used instead. But only in the localized versions.
That of course means that you have to translate these scripts depending on the locale set in your office suite, otherwise they are full of syntax errors...
