I think Netbooks are a solid replacement for a PDA if it's with you, but IMO they tend to be a poor compromise between a primary machine a portable one. They don't fit in my pockets and if I have a bag I only really care about weight at that point. I always have a cellphone that works as a PDA, if I am going to get stuff done I want decent keyboard, a high resolution screen, a fair amount of ram, and a HDD large enough that I don't have to care about what I am storing.
PS: Many "normal people" tend to have a web browser (word processor etc) and a IM client open at the same time so Netbooks resolution is still a fairly large sacrifice for most normal people. I use a 15" laptop with a 1920 x 1200 screen and it's great, I could drop down to 1680 x 1050 but that's low IMO.
Maybe, but I find the eee a lot easier to carry around when I am at conferences. Sometimes you need to move pretty quickly, and the eee makes that easy. A big laptop has to be closed and stowed away in your backpack. The netbook just floats around with you. (It's hard to describe, so try it sometime.)
Many "normal people" tend to have a web browser (word processor etc) and a IM client open at the same time so Netbooks resolution is still a fairly large sacrifice for most normal people.
That's why the non-Windows netbooks go for a GUI that uses virtual desktops (or rather, all the apps are full-screen). This works very well; the notification tray gets your attention when your IM window needs you, but otherwise you just keep the browser maximized.
(This is not how I use my netbook, FWIW, but I am not a "normal person". I do my IM-ing from inside emacs; so I usually have 3 xmonad desktops; emacs, an xterm, and a full-screen web browser.)
Anyway, the reason why people need 1900x1200 on a laptop is because they don't know how to manage windows properly. Learn that, and you can do fine with a 9" screen.
Anyway, the point of the 9" screen and 8GB flash drive is that it makes the machine easier to carry around with you. You can pick it up and shove it in your bag without worrying about whether the disk spun down or not. The battery lasts 6 hours, so you don't have to constantly wander around looking for an outlet. You just open the thing up, and can work for as long as you like. It's not heavy, so you don't even know that that computer is with you.
It's not just a "price point", it's about having the power and convenience of a "real computer" with you where ever you go.
(And FWIW, I don't really mind working on my 9" EEEPC all day. The screen is stunning, much better than my 15" Thinkpad. The keyboard is nasty, however, so I tend to carry around my HHKB with me. But with that, there is basically no productivity loss. I can, and do, work all day on that.)