Changewave claims anticipation for iPad exceeds initial iPhone anticipation. This is surely an artifact of Changewave's sample, as Changewave admits surveying a segment of the technorati – the "frontline of technological change" – whose demand for gadgets is likely not reflective of the general population.
However, the interest in iPad as an eReader platform might really mean something. Cell phones are in much broader use than specialty products like eReaders, and sample bias toward the technorati might easily skew results into uselesness, but the technorati is the very population likely to be interested in esoterica like eReaders. The survey's prediction that iPads will soon dominate eReaders is thus interesting in a way the survey results comparing iPad demand to iPhone demand was not.
To compare iPad and iPhone demand, one wants data drawn from a different pool. For my purposes, I'd like data drawn from back-to-school sales: if the device will replace students' physical notebooks and textbooks, this should be reflected in back-to-school demand. Of course, this demand may be delayed until it's obvious whether iPads will offer content with the right digital rights. It's easy to screw up content's appeal with bad DRM.