If it hasn't happened already it seems poised to happen sooner or later, albeit usability is to some extent in the eyes of the beholder.
Certain pages on this site lead to a "reported attack site" warning for Firefox 3 users which is apparently a feature built into Firefox 3 and provided by Google.
Wine is an Open Source implementation of the Windows API on top of X and Unix.Think of Wine as a compatibility layer for running Windows programs.
Here is an interesting article about "libre" web applications which are open source and free of restrictions on use.
First of all I want to make clear that I always liked FTP. And I still prefer it over uploading my files through a web-interface, but I now have found quite a big reason why FTP really really sucks.