Difference in Transparencies on IE9 and Other Browsers

I noticed today that that the Front Page of the Verge displays the transparencies differently in all three mainstream browsers. Firefox and Google Chrome are more or less similar with slight variations but IE9 is drastically different;

IE9

Ie9_medium

FF12

Ff12_medium

GC19

Gc19_medium

So is this a known glitch or is it because no one cares about IE?