While there seems to be some controversy about the actual numbers, the graph below tells the clear story of the decline of Internet Explorer (yeah) and the growth of Google Chrome. That is what is important here. The reason developers are doing scissor kicks over this is because Microsoft has again and again ignored standards that should provide consistency and efficient development. Microsoft took their own road and produced crappy browsers time and time again, which only forces developers to double their front-side development efforts (cost) to create acceptions and work-arounds to deal with IE. The result for users has continuously been sub-par experiences. I could go on, but I won't.
In contrast, Google Chrome follows the standards and quickly adopts new standards (HTML5) as they come to the table.
The good news is to see Google Chrome take the pole position, and the farther IE drops, the better and cheaper websites will become.