Steve Jobs supposedly said the iPad would be the most important thing he's ever done, and he's done plenty.
The iPhone has been a big deal because it successfully mainstreamed the existing smartphone category. The iPod touch accounts for roughly 30% of current iPhone OS devices and is the heir to the iPod which successfully mainstreamed the also already existing MP3 player category.
To be a bigger deal, the iPad will have to not only mainstream the computing appliance, but create the category.
Can Apple succeed at that?