iPad for the right age?

The iPad and tablets allow for incredible new forms of learning. They can help us increase engagement and creativity and comprehension. The touch-screen model makes programs like iBook act so real, and the interface is so intuitive that it almost seems like we're reading a real book. And this is where I keep going back to my Ed psych 101 course with questions.

Isn't there a stage in early childhood development where kids don't know the difference between abstract notions and real objects? For example, one where they think the apple on the page is a real apple, or that if they close their eyes they really do become invisible?

Which leads me to, does learning about objects and physical phenomenon in a virtual world (iPad) translate to understanding in the real world? Is it better for a kid to learn about shapes by playing with virtual blocks or real blocks? If they learn in a virtual world, can they then do that in the real world? It seems that these types of questions will help us determine if there is such a thing as the "right" age to start kids on computers, tablets, smart phones, etc.

Of course, the bigger question is, with all of the "work" we all do on computers, using the computer's processor to enhance our own capabilities, which then produce real objects (i.e. computer-aided drafting and design, statistical analysis, etc.), is work done on a computer just as "real" as work done in the physical world?

This is a great group of educators, and I would love to hear your thought on any of these questions.

Stuart