So last week I received an interesting question from a customer. He complained that in Chrome on Mac, the category 'Soßen und Dips' ("Sauces and dips") on the german (obviously) version was rendered as 'SOSSEN UND DIPS' (wrong), rather than 'SOßEN UND DIPS' (right). Notice that ß and SS are semantically identical - a latin1 collated database will consider those strings to be identical.
On Internet Explorer, the ß was displayed fine.
It didn't take long to figure out that the menu item had text-transform: uppercase applied, and that this caused the transform of ß to SS. What's more, Safari and Firefox also displayed SS instead of ß. My Google search led me to page https://bugzilla.mozilla.org/show_bug.cgi?id=354451 . This page indicated that transforming ß to SS was deliberate, and not a bug at all. Der Spiegel suggests that ß should, in capitals, always become SS.
So now I only need to convince the customer that their browser can spell their language better than they can.
As an interesting aside: a basic test case to check browser behavior sees Internet Explorer 9 also rendering SS, not ß. Changing the document mode down to IE7 shows ß again. The actual online page is in IE9 mode, and does not have a X-UA-Compatibility meta tag. The question then becomes, why does it show ß? No idea yet.