Panorama Photo Mode Coming to iPhone 4S with iOS 6
iSight camera specs for iPhone 5 (left) and iPhone 4S (right)
According to Apple's iPhone model comparison page, iPhone 4S users will not be left out of this feature addition, with the spec comparison listing "Panorama" as one of the features of the iSight camera on both the iPhone 4S and 5. The feature will not be available with the lower-quality rear camera found on the iPhone 4.
Update 1:58 PM: The iOS 6 golden master released to developers today does indeed enable Panorama mode on the iPhone 4S.