"In less than a week, you’ll likely be typing faster on iPhone than you have on any other small keyboard," says the gent in Apple's iPhone keyboard demo video. He must be sincere--he says the same thing in almost the same words later in the video.
I'm not going to tell him he's wrong until a week has passed--but almost 48 hours into iPhone usership, I can't type on the thing anywhere near as quickly as I can on a BlackBerry or Treo or other devices with tiny real keyboards.
There is one way that I think Apple could make input on the iPhone incredibly quick. And that would be to implement a fingertip-driven variant on Graffiti, the simplified handwriting recognition system that was the primary way to get text into Palm devices for years. (Graffiti started out as a third-party app for Apple's Newton, incidentally--so if it, or something like it, ran on an iPhone, it would be a sort of homecoming.)
As implemented by Palm on its handhelds, you scrawled Graffiti characters into a little box on the bottom of the screen. But third-party apps such as Graffiti Anywhere let you use the entire screen, which--for me at least--improved accuracly dramatically. I'm not sure if any mobile input solution has ever let me get text into a handheld as quickly.
So I'm thinking that the iPhone's giant-sized screen would allow for extremely fast, accurate input--and the fact that you'd be doing it with a fingertip rather than a stylus might help. And the precision required to hit the iPhone's teeny tiny keys would be a non-issue.
I can't see Apple doing this, and for now, no third party would be allowed to. And I'm not sure whether someone could make a Graffiti-like system that didn't violate any patents. (Graffiti itself was bedeviled by a Xerox lawsuit, although Palm eventually prevailed--after it had dumped Graffiti for the less friendly but clearly legal Graffiti 2.)
All of this makes the notion of something similar on the iPhone a pipe dream...but an intriguing one...
There's no way text input would be faster in that way. You will certainly take twice as much time to draw a single letter than to type one in whatever keyboard. I'll grant you though that your accuracy will improve greatly for you will be writing what you want. And sure the response of the device will be immediate to your input so you won't feel any delay giving the impression of being faster.
Maybe you should watch this YouTube video.
This guy says, "People who can't type fast on this phone are retarded" and demonstrates his own skill at typing on the iPhone:
http://www.youtube.com/watch?v=lKfhxMpEGpM