The HN discussion on the Nexus had many users coming out of the woodwork discussing how they wanted to buy one, touting the virtues of the size. In SV, I also know of other techies who regularly use a laptop but rarely use their iPad (or choose not to buy one). The iPad is slightly too big to carry comfortably in bed or on a couch to read while the iPhone is too small. And since I already have a 13' Macbook (soon to be Air), there isn't much that a 10' iPad has over it with regards to portability and function.
I wouldn't want a bigger iPhone (even though I know it's going to happen) because it already seems bigger than I'd like for a pocket phone.