Google Trends is an interesting indicator to watch to fact check rumors and try to anticipate. I've used it before and it proved very interesting.
So what does it tell us? Interestingly, the iPhone 4S was already rumored as the iPhone 5 (few saw the 4S coming...) so this graph allows to compare the anticipation for both the 4S and the potential 5.
Bottom line: we're currently standing at exactly the same volume level we were 1 year ago, when the iPhone 4S was launched on October 4.