What he said
"Oh, and MY personal favorite: like a phone, it's ALWAYS ON, always in touch with notifications, and has near zero boot time when i want to look up something quick i just saw on TV or heard in a discussion. For me, no boot time is the killer app!"
That's definitely a killer app for me, although in my specific case it will mean that the thing is actually used, rather than just left in the dev cave.
I have a tablet PC netbook type thing, which I bought partly for this very reason. That was before I added an iPhone to the dev cave. It is far quicker to reach for the iPhone than the tablet, now if only it had a bigger screen ...
Also : @ all the "my netbook can do that!" crowd. Even if your netbook has a touchscreen (mine does, neener neener) there is no touch web browser experience that is as good as Safari on the iPhone on your netbook. I can't abide it on the desktop, but on the iPhone it's very nice indeed. Nothing on my netbook is as good. FF with touch extensions, not so much, still eats CPU when you scroll, jerky, natch. Opera probably comes the closest, but still not quite as good. IE is surprisingly good, but suffers from it's general IE-ness.
What I'm saying here is that yes, your netbook can do that, but it can't do it as well. Primarily because none of the apps on your netbook were designed around a touch specific device and UI.