"Skate to where the puck is going"... The iPhone is as revolutionary as the first Macintosh, if not more so.
Here is what I think: Computers are generally too hard for people to use, or better phrased, computers have too steep of a learning curve that out weighs the benefits people want from a computer.
I know this is hard to believe, but most people don't like computers. Computers generally "get in the way" and cost too much. Most people get home computers for only a few reasons:
1. Email.
2. Surfing the internet.
3. Games.
4. Digital pictures.
5. Digital music.
The iPhone has the potential to make the desktop computer a thing of the past... or at least not necessary for the general population. The iPhone is an appliance, its simple to use and could do all 5 things I listed above, albeit number 3 is somewhat limited but that is what the Wii or Playstation3 is for.
In general, I believe the iPhone will raise the "standard of living" when it comes to information access and computing for the mass of the world's population. Revolutionary.