Successful new gadgets always seem to occupy a clearly defined place alongside, or replacing, existing devices. The Flip filled a previously empty niche for a small, cheap, simple video camera. How was the iPod better than existing portable music players? It fit 1,000 songs in your pocket, with a fun interface that let you find them easily. Why buy an iPhone to replace your existing mobile phone? Because there was a clear need for a modern handheld general-purpose computer.

But how much room is there between an iPhone (or iPod Touch) and a MacBook (or other laptop computer, running Windows or Linux or whatever)? What’s the argument for owning all three?

If Apple is known for anything, it's known for innovation and breaking new ground. So if the pundits have been wrong before about the "what's next" from Apple, what will an Apple Tablet really do?