I'm not really a soccer fan (football, I know) but I've hear a number of people here, and in real life as well, complaining that they can't watch the World Cup games because of that irritating horn. I had to watch just enough of it myself to see and understand how irritating it really is. No way could I watch that, even if I was a fan.
Just happened upon this today though, it might help some of you guys enjoy a match or two. Website is all in German, but translatable, and you can get the gist by looking it over carefully. Guy has created a software filter to rid the matches of the sounds of those damned horns.
http://www.surfpoeten.de/tube/vuvuzela_filter