Apple's tag-line for the iPhone 3G is "Twice as fast. Half the price." However, if you take a closer look at the numbers you'll see that the new iPhone works out at $40 dearer than the current model.
$199 + $240 = $439
That's a $40 increase compared to the price of the current iPhone.
It also seems that the iPhone 3G will need to be activated at an Apple Store of AT&T store, there will be no online ordering, and there may be financial penalties imposed on those who do not activate their iPhones within 30 days.
The devil's always in the detail ...