Tom's Hardware had a recent article on the futures of the various browsers. In summary the author predicted that Firefox would rise again after overcoming some of its recent problems. He calls 2011 "...A catastrophic year for Firefox." I agree.
Perhaps I hadn't been watching closely enough but what surprised me was the ongoing precipitous drop for Internet Explorer as shown in this chart.
The data comes from StatCounter. Maybe there's an agenda there but I'm not aware of it. Tom's Hardware doesn't seem to have a dog in the fight. The author says "take any market share predictions with a grain of salt."