Why is it that a "standards-based" browser that passes the Acid2 (like IE8) still doesn't render certain pages correctly, and others (like Opera, Firefox 3 Beta, etc.) do?

try opening this link in IE8, then in another standards complaint browser. notice that IE8 doesn't display it right.
http://www.windowsmarketplace.com/content.aspx?ctId=391

weird, huh?