For years German type designers (and designers in general) led debates if they needed a capital eszett (lowercase eszett: ß, sometimes called "German B" too). The background was the unclear use of ß in an all-caps word, a name for example. Seeing a lowercase letter in an all-caps word is weird, so it's also been substituted by an SS, but in a name an ß isn't equal to SS.
Then some type designers started making their own versions of capital eszett, and the others responded that historically such a glyph never existed, since ß is an ss ligature and it still looks weird (which I think it does).
And now it's official: Unicode 5.1 contains the "capital sharp s" with the number U+1E9E. Yay!