Has Apple stated any meaning for the 'S' in the iPhone product designations '4S' or '3GS'? Does it mean the same thing in both product names?
As of October 2011 when this was first asked, there has been no official answer stated. With the 3GS, Apple officially stated "the S is for speed." There has been no comparable explanation given for the 4S.
HOWEVER, in an interview at the All Things D conference, Apple CEO Tim Cook stated, "some people might say it stands for Siri or speed. We were thinking of Siri when we did it."
So the official answer is that the S in iPhone 4S stands for...
Apple itself hasn't released any information regarding the S. The three most common theories out there seem to be "S" for "Siri", "S" for "speed" and "S" for "Steve". My guess is the "S" means "speed", like the iPhone 3GS.
The S in 4S stands for the same thing as the S in 3GS. But as of October 2011, I think it is safe to say it is not Siri.