The biggest change besides the slightly taller chassis of the iPhone 4S (4.54" vs 4.5") are the notches in the steel band surrounding the iPhone 4S. Apple's engineers have redesigned the reception area after the "you're holding it wrong" drama last year, and have moved the notch from near the headphone jack on top of the iPhone 4, to above the mute button on the left side of the iPhone 4S. Since the new iPhone sports new dual antenna design, there is one more notch above the microSIM slot on its right side, making them four in total.
This new antenna design, however, could run Apple into legal trouble with Samsung, should the Koreans decide to pursue its patents on technology that "intelligently switches between multiple antennas", which they bought from Aalborg University in 2007. Professor Gert Pedersen there says that Apple's statement about the antenna sounds an awful lot like what his team sold to Samsung four years ago. "Improving on the innovative stainless steel external, dual-antenna design of iPhone 4, iPhone 4S is the first phone to intelligently switch between two antennas to send and receive”, said Phil Schiller when he took the stage during the iPhone 4S announcement.
Samsung's patents now cover switching antennas when the phone is held in landscape or portrait mode, which presumably will also be a feature present in the new iPhone 4S, so Professor Pedersen had some more comments on the issue:
Professor Pedersen might certainly be planting ideas in Samsung's legal team heads, despite that the Koreans allegedly decided to keep it down a notch with the counter-lawsuits, in the hope that the new CEO Tim Cook will be more reasonable in the litigation department.
source: Comon via 9to5Mac & Xaluan