From Habrahabr:

citiuscode: Metro style is very beneficial for Microsoft, and the fact that if many sites start to "cut" under this style, then the issue of rounding of corners, shadows and CSS gradient properties is automatically solved =)

Citiuscode: In IE of course.

shmaltorhbooks: that is, you think they changed the logo so that you can hit the normal implementation of css properties in the browser and no one will burn?)