At this writing, Apple's homepage sports the faux word "Resolutionary"--text rendered in graphic form--along with an image of a hand touching the new iPad. Before you run AppleInsider's code, the default webpage uses a 471 by 93 pixel for the Resolutionary image, which weighs in at about 7kb. After you run the code, Apple substitutes a version of the image that doubles its width and height, yielding a 942 by 186 pixel image that weighs in at about 18kb.
The large iPad graphic starts out much larger, so its Retina version is, frankly, enormous. The original image measures 1454 by 605 pixels and 113kb; the Retina version is a whopping 2908 by 1210 pixels and 360kb. The Resolutionary image is about 2.5 times larger in its Retina version, and the hand and iPad image is more than 3 times larger. It's those Retina-friendly increased image sizes that , but in this case the Web images wouldn't gobble up your iPad's remaining space. Those images could, however, gobble up plenty of extra bandwidth--which could be quite significant if you're using your new iPad's cellular connection.
When Apple's website loads those larger Retina images, it still squeezes them into the space taken by the smaller versions. That is, the 2908 pixel wide iPad image is only displayed by default on the iPad as 1454 pixels wide. The doubling of the image empowers the Retina display to work its visual magic.