Almost Half Web Users Ready for HTML5
Firefox 3.5+ is used by almost half of their HTML 5 ready users, while Internet Explorer 8 is used by half those who are still surfing the web with HTML 5-incompatible browsers. The way they were able to tell? By using HTML 5 video as a guideline.
Even as the market share for Internet Explorer continues to drop, it still accounts for about half of all Internet traffic. IE9 is going to support HTML 5, but given the rate that web users upgrade their browsers, it will still be a while before they will all be using compatible web browsers.