The fine folks at Chipworks have taken a closer look at the new iPad, particularly at the upgraded A5X processor. The die size was apparently increased by 35% to accommodate the quad-core graphics processing unit. They were also able to confirm that the new processor was made by Samsung using a 45 nanometer CMOS process. Chipworks also looked at the parts iFixit pulled out from their Austrlian iPad, and identified particular RAM, Wi-Fi, LTE, audio, and power management chips; much like the 5 megapixel camera unit, a lot of these were recycled from the iPhone 4S.
It seems like although the screen is killer, there aren't a lot of dramatic changes under the hood of the new iPad. That said, I would love to see some up-close pictures of the Retina display's structure. We can see the difference in pixels for ourselves, but during their announcement, Apple had explained how the wiring was put on a separate plane in order to avoid signal confusion and cram pixels in together as closely as possible; seeing a cutaway or other close-up of what's going on behind the pixel layer would really showcase the biggest change in the new iPad.