I had a chance to try out an iPhone 4S over the weekend, and I think Siri, the voice recognition service built into the phone, is potentially another Apple game changer, just as the touch interface on the original iPhone was a game changer.
While playing around with the iPhone, I discovered that the little pop up keyboard used to input text in virtually every application on the iPhone has a Siri button. If you tap it, the phone goes into voice dictation mode. Instead of laboriously tapping away on the virtual keyboard, you can just talk. I was able to try only a few sentences, but some of them were quite long, and the transcription was perfect--no mistakes.
Oddly, even Apple is not highlighting this feature. Instead, the ads for the iPhone 4S show the ability of Siri to answer queries like, "What time is it?" or "What is the weather in New York City?" This feature worked, but I was underwhelmed by it, as there is a slight lag while Siri goes to look for the information, and for things like the time or the weather, you can get it faster with a couple of taps. But the dictation is magical, and I can't wait to see Siri available on Macs.