Via email from Google to one of my clients:

In order to continue to improve our products and deliver more sophisticated features and performance, we are harnessing some of the latest improvements in web browser technology. This includes faster JavaScript processing and new standards like HTML5. As a result, over the course of 2010, we will be phasing out support for Microsoft Internet Explorer 6.0 as well as other older browsers that are not supported by their own manufacturers.

Ahh, IE6. The bad old days.