Since there are so many panorama camera apps at the App Store. There is no reason that Apple ban it from other devices using it. The newly-added Panorama feature in iOS 6 is not exclusive for iPhone 5 only. It works with iPhone 4 and iPod Touch (5th generation) as well.
This is confirmed at the Apple.com website. We have also tried this awesome panorama feature with the latest iOS 6 GM version. It works pretty well as expected, since iPhone 4S is already using the 8-megapixels camera.