Not on your iPad
Though this may not matter if you have an iPad 3G, this is sure to annoy users of the wifi-only model. It seems that there is no way (without a jailbreak) to tether your iPhone to your iPad. Not over USB, not over Bluetooth. And just when we were getting excited because AT&T is finally allowing for tethering.
Where is the evolution? This is more of a de-evolution. Is there hope that we may one day be able to use the iPhone as a portable hotspot? Do it, Apple!