As had been rumored and shown in leaked images, the iPhone 5 does indeed use the new Apple-backed nano-SIM standard that is 40% smaller than the micro-SIM standard found in the iPhone 4 and 4S. Apple did not mention the change during its media event, but the company has confirmed it in an iPhone model comparison.
The iPhone 5 appears to be the first device to use the new nano-SIM standard, and carriers had reportedly begun stockpiling the new cards as long ago as July before starting to distribute them to retailers earlier this month in anticipation of the iPhone 5 introduction.
Article Link: iPhone 5 Confirmed to Use New Nano-SIM Standard