After a few weeks of internal discussion, we’ve decided that starting September this year, we will gradually remove support for IE6. Why did we take this step? Simple, toward a better web future. Many websites, even Facebook and 37signal have taken this necessary step as well, and Microsoft has provided a force upgrade to Internet Explorer 7 since February this year. So we believe that this would be the best time to focus on developing real good standards-compliant websites that does not require any IE-specific hacks.

You can find more information about this matter here.