According to 9to5Mac,who have apparently has a source with some hands on time with iOS 6, have delved into the code to find out more about the processor we might see in the iPhone 5.
The report claims the new iPhone running iOS 6 includes Darwin Kernel Version 13.0.0 and the processor is an ARM S5L8950X. Apple currently uses the SL8940X on the iPhone 4S and the SL8945X on the new iPad. Their source says Apple is refers to this process as the A5-*** internally. To protect the source, they have not shared those three letters or numbers that make up the actual product name.
As for the RAM, expect 1GB, which is what we have now with the new iPad.
This prototype is using a SoC (system on a chip), with the GPU chip called the SGX543RC. It’s an unknown chip, so also unknown are the specifications.
So, faster processor, improved GPU and more RAM. All these sound plausible.