Microsoft just announced that it started work on Internet Explorer 9 three weeks ago. Steven Sinofsky, the president of Microsoft's Windows and Windows Live division, showed an early build of IE9 during his PDC keynote today. In this presentation, Sinofsky announced that Microsoft will focus on support for new standards like HTML5 and CSS3, as well as developing a faster JavaScript rendering engine. Sinofsky candidly acknowledged that IE8 did not do well on the Acid3 test, though this early build of IE9 only scored a few points higher than IE8 (24 vs. 32).

According to Sinofsky, there is still a lot of internal discussion about how much of HTML5 to support in IE9. HTML5 is still in its draft stage. Sinofsky did not say when the company plans to release IE9.