I am in Switzerland for Christmas. I launch a new Firefox install. Firefox loads the Firefox Start page, featuring Google search. The page is in German.
About 64% of people speak Swiss-German dialects (and German as well), 20% French, 7% Italian, based on geographical boundaries. People in these different areas do not necessarily have a working knowledge of the other languages (even though they should). This means that Switzerland is not a German-speaking country in the same way that Germany is.
For this reason, it is not ok to present pages in German by default when you believe that the user is located in Switzerland. Even if you think it is ok to make an clearly erroneous guess, then you must provide an easy way to switch to the other national languages as well as English. This ability must be available directly on the home page and must be a one-click operation. This is how Swiss sites typically behave.
The Firefox home page is particularly badly designed in this respect. You can't switch language directly on the page. In fact, to change the language, you have to know German to go to the advanced search preferences ("Einstellungen", and then find the menu to change the user's language), which does not make any sense. Somebody without a knowledge of basic German or an awful lot of patience will simply not be able to do it at all.
Other countries are multi-lingual, including but not limited to Belgium and Canada. I think it is time that companies that design localized sites become aware of this issue.