As people keep reminding me, I worked on Apple’s last wildly-hyped handheld communication device. It’s easy to draw parallels between the Newton MessagePad and the iPhone. You’ve got the great industrial design, powerful and innovative hardware and software, and “change the world” attitude. You’ve also got out-of-control expectation-building, a new input method the CEO says you’ll get used to eventually, and risky technology compromises with awkward excuses (EDGE? Say what?).

But unlike the MessagePad, the iPhone is an evolutionary entry in a well-established category. The iPhone is actually a pretty conservative product (just as the iPod was). Everyone knows what a smartphone is — this is just a smartphone with Appley goodness. The hype seems extreme, but it’s tame compared to the crazy fantasies people (including Apple management and marketing) painted for Newton on the then-blank canvas of the handheld computer market

Of course evolution is the smart thing to do. A disappointing iPhone could deflate the widespread positive perception of Apple generated by the iPod. That perception is probably Apple’s most valuable asset. The iPhone has to walk the fine line between excitement and disappointment — to get the early adopters to stand in line, sign up for the two-year plan, and be just satisfied enough to not trash Apple’s reputation while the next models (the ones with 3G and whatever other big fixes are needed) are developed. Newton tried to walk the line but lost its balance almost immediately. Here’s hoping the iPhone stays upright!