Jeff Yurek of Dot Color spent some time exploring the color performance of the new iPad. He, like many others, noticed that the colors on the iPad were richer than the iPad 2 and hypothesized that Apple improved the color filters.
After analyzing various spectrum charts, he concludes that Apple limits the light leakage of the display by improving the color filters. You can see the improvement in an example photo on his website. The side-by-side shot shows a greenish hue leaking through the blue on the iPad 2, and the rich blue of the iPad third generation.
Though pleasing to the eye, he notes that these color filter improvements require 20 to 30 percent more power to maintain the display's brightness. This may partly explain why Apple opted to go with a large, 42.5-watt-hour battery in the new iPad.