Why on earth would you want the tablet - which is a mobile computer in itself - to have to "tether" to an iPhone for internet connectivity when they could just build it into the device itself?
Precisely. It would be for whenever said user is away from a hotspot (their home, a coffee shop/bookstore). Tethering simply would be ideal if in an area/situation where a free and consistent wifi signal is not available.
I suspect that Apple won't make the no-data plan tablet completely insulated (a la iPod Touch). I'm sure it will have tethering capability and one could assume that they would be charged some rate/MB or some rate/minute of usage to their existing iPhone or other capable device contract.
