In the mainstream computer media we are seeing reports that Firefox (and others) are taking market share away from IE but that IE still has something like 90% market share. That surprised me when I realized that I know hardly anyone on the net frequently who still uses IE. In an attempt to be a bit more rigorous about the process I looked at the web stats of a number of sites that I have access to, my own blog stats, and then at the blog stats of a number of other popular blogs - mostly, though not exclusively, from my blogroll.
The basic summary is that Firefox appears to have significantly greater market share than reported in the mass media and IE has far less market share. While there were outliers such as BoingBoing, where Firefox has a greater share than IE (both account for roughly a third of the visits), in most cases Firefox has over 20% and IE generally had a share somewhere under 66%. Both these figures exhibited significant varience so that the Firefox number is anywhere between 16% and 32% and the IE one anywhere between 53% and 74%. The Firefox number does not include (in almost all cases) the Mozilla number, typically 3-5%. Mozilla and all those other alternative browsers make up the balance between the two figures usually about 10-15%.
Initially I thought I could draw some other conclusions about how left-wing blogs were more Firefox than Right-wing ones and while it is possible that this is true, I suspect the sample size is too small for this to be statistically significant. What is clearly significant though is that blog-readers are using Firefox at a significantly higher rate than reported in the mainstream media. This is a very important trend because, as the recent blogads survey showed, bloggers are overwhelmingly those people that are described by marketers as "influentials". In other words what bloggers do today others are likely to do tomorrow.
In the interests of full disclosure here is a table of the blogs checked and the browser share reported