Speculation: the A4 is PowerPC and OS4.0 Will Double it's Speed
As we've discussed on this site plenty of times before (and the Internet has beaten it to death as well) - Apple's decision to require all apps that run on the iPad (and iPhone) be built in Xcode is curious and somewhat ridiculous.
Many chalked it up to Apple wanting control and to make sure that competition (Flash, others) didn't have a chance to really grow on the platforms that Apple controls.... but what if that were not true at all.
What if, Apple really put a different CPU into these newer devices (The A4) and is actually running ARM emulation to be backwards compatible. What if OS4.0 gave Xcode compiled code the ability to run natively on these devices and instantly we saw a 50% speed improvement on these devices.... would that make the sacrifice of being able to code in other frameworks less of a problem?
Before you say this is not really possible, consider what we have taken for granted: The A4 is an ARM based CPU. We don't know this for sure... the die size of the CPU is much larger then it needs to be to support this CPU. In addition, the PA Semi team that apple purchased was actually working on low power PowerPC dual core CPU's.
This article breaks it down in more detail and is a great read for the speculators and conspiracy theorists out there: The Genius in Apple's Vertical Platform - steve's blog