A Korean newspaper has recently said “The next iPhone will be here in limited supply in April, and be more power than 
previous models”. They believe that Apple will be test running the next-gen iPhone to corporate sponsors as soon as April.
Many other blogs are skeptical about what the Korean newspaper said, as Apple never usually test run devices except for workers at Apple working on the product.
The report also talks about how the next iPhone will have the ARM Cortex-A9 CPU, which could offer speeds up to 2GHz which is a lot faster than what we have now. All of us expect the device to improve as it must for Apple to appeal to users with a prior iPhone. But a dual core CPU would work well with a multithreading GPU and would help push those HD graphics.
Sam's Blog 