CUPERTINO, Calif. ( TheStreet) -- It's the rich features -- not the expensive device -- that Apple ( AAPL) will be selling today when it unveils the hotly anticipated Apple Tablet.

If comments made by McGraw-Hill ( MHP) CEO Terry McGraw about the Apple Tablet on CNBC Tuesday are true, the Tablet will run on the iPhone operating system.

That little slip pretty much dashed any hopes that the Apple Tablet will usher in an advanced generation of mobile computing.
Tablet
People queue up for Apple outside the Yerba Buena Center for the Arts.

With months of anticipatory imagination in place, it may be hard for the Tablet to live up to expectations. With the Tablet running on the iPhone platform instead of a computer OS -- and knowing the limits of a smartphone platform -- the bar already seems to be lowered a bit.

You can't have it all, says Northeast Securities analyst Ashok Kumar. With a large, brilliant-color touchscreen and at least one -- and probably two -- wireless systems running, the Tablet will suck a lot of electricity.

"There's always a big tradeoff between processing power and battery life. And I think it will be a compromise on both fronts," says Kumar, referring to Apple's decision to use the more power-efficient iPhone OS.

So while pretty, the Tablet will fall somewhere between an overpriced PDA and a woefully underpowered notebook.

This glorified e-reader, however, opens a new chapter in Apple's grand plan to be a modern media hub.

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