There's a lot of speculation about what's inside the A4, Apple's custom and ultra-power-efficient chip that powers the iPad. Nobody knows for sure because, like all their products, it's a seeeeeecret. Until now.
According to Jon Stokes' well-trusted sources, there is no Cortex A9 dual-core inside Apple's A4, but just a single Cortex A8 and a PowerVR SGX GPU. According to Jon, it's probable that Apple has taken out a lot of the communication, image and video blocks that the Cortex A8 uses, making it an extremely lean and efficient processor.
Do you have to care about this? No. As Jon says, the important thing about the iPad is not its specs and how many polygons it can push. That doesn't matter to normal consumers, that just matters to feature-list-obsessed geeks. What would be important for consumers is that the iPad provides a smooth experience, using a user interface different from standard computing. [Ars Technica]