But Apple is a more benevolent force than Microsoft in that they owe their market share to the quality of their products rather than to taking over the PC standard from IBM.
Meanwhile, Linux is eating their lunch in this segment.
Well, no. Apple's idea of a cheap, lightweight computer costs $300 to $500, fits in your pocket, and (optionally) doubles as a cellphone.
(If you don't agree with this interpretation of Apple's product line, wait a couple months after the official third-party iPhone apps arrive and consider it again...)
You can't type on the iPhone very quickly, of course. It won't run emacs or vi very well. It probably won't run a web development stack, or a decent Java compiler. So if what you really want is something like an EEE you should buy an EEE. There's no reason why Apple's idea of a cheap, lightweight computer should match yours...
Whether or not the iPhone is in the EEE's market segment depends on what you think that segment is. I'd say that it's squarely in the "super-light super-cheap portable box for checking mail and web" segment. If you're talking about the "light, cheap portable box for fixing your website via SSH from a coffeehouse in the Florida Keys" segment, it's a lot less clear.
Pesonally, I have a phone that runs both ssh and vi (a Samsung i760 Windows Mobile 6 phone with a touchscreen and slideout keyboard), and I'm still interested in getting an Eee.