The advanced media was calling this new A5 a single core application processor, and Apple themselves on their product specification page call the new A5 a single core application processor. Sometimes, when we get inside technology, we find that things are not always what they are supposed to be. The new A5 processor die is not a single core processor, but contains a dual core processor. Either Apple is only utilizing one core or they are binning parts. Parts binning is a common process in semiconductors where devices are segregated (binned) based on meeting a subset of the overall requirements, in this case they could disable the "bad" core, this increases the usable die per wafer, lowering the cost.
In addition to being a dual core processor, Apple also snuck in a new technology process for manufacturing the A5. The previous generation A5 was manufactured using Samsung Semiconductors' 45 nm LP CMOS process the new A5 is manufactured using Samsung's new 32 nm high-k metal gate, gate first, LP CMOS process technology. The process allows for a 41% smaller chip that reduces costs by fitting more dies on a wafer, improves performance, and lowers power consumption.
Read More [via MacRumors]