According to Google Analytics my blog readers use: Firefox -- 45.16% Internet Explorer -- 40.80% Safari -- 10.93% Opera -- 1.51% Konqueror -- 0.05% (Linux die hard!)
Firefox has over-taken IE. Both Safari and Opera are up about 1% each over the last time I looked (sometime last year). Things are slightly more diverse. Obviously, Firefox continues to plow on through.