I don't like netbooks because they're slow and you need a table to use them properly. Especially in airplanes. Slate form factor is easier to carry, lighter and they manage well most places; You can put them where magazines can go.
Granted I can't do all of my sys admin stuffs, because iPad aren't jailbroken yet (yea yea), but right now I got ssh, rdp and vnc on it already to do 90% of what I need. If I need to do plenty of text entry/commands, I just prop the slate up on the table and flip open my bluetooth keyboard (stowaway full sized foldable keyboard).
I'm not saying it's superior in all cases to netbook, but it's a very versatile form factor. And the amount of functionalities they crammed in it (digital compass, accelerometer, great doc manipulation, etc) means it can go places where netbooks don't. imho this is a form factor to watch.