The Apple iPad will likely usher in a revolution in "common man/woman computing" where everyday, ordinary people (mostly non-techs) will be able to do useful things on their iPad.
The iPad should be great for older people, seniors, children, students (K-College), and just about everybody who doesn't need the latest tech bells and whistles.
It is all about the user experience, and doing very common tasks (E-mail, web browsing, social networking, e-book reader, watch movies/TV shows, play music, edit documents/slideshows, play some games, etc.).
While the high-end gamer, the programmers, and the people who need super-fast processors will not be happy with the iPad as their primary computer, I see Apple building a line from the iPhone/iPod/Touch and now the iPad to form a bridge up their higher end models, for users who need that power (Macbook Pro, Mac Pro, iMac, etc). Good job Apple!
If anyone thinks for a minute that Apple is stopping at the iPad, they are sure to be surprised at how Apple's future products will incorporate concepts from the iPad and their other models.